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CONTEMPORARY    SCIENCE 


EDITED  WITH  AN  INTRODUCTION  BY- 

By  benjamin  HARROW,  Ph.D. 

AUTHOR  OF  "from   NEWTON  TO  EINSTEIN,"   "EMINENT 
CHEMISTS  OF  OUR  TIME,"  "VITAMINES,"  "ESSEN- 
TIAL   FOOD    factors'"' 


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CONTEMPORARY    SCIENCE 


COPYRIGHT,   1921,   BY 
BONI  &  LiVERIGHT,   InC. 


PRINTED  IN  THE   UNITED   STATES   OF  AMERICA 


The  men  who  have  been  good  enough  to  cooperate  with 
me  in  the  preparation  of  this  volume  are  masters  of  their 
respective  subjects ;  and  what  they  say  represents,  in  sum- 
mary form,  some  of  the  latest  achievements  in  science. 
The  book  does  not  pretend  to  be  an  exhaustive  treatise, 
but  it  does  claim  to  review  some  of  the  more  recent  and 
more  suggestive  work. 

My  thanks  are  due  to  the  distinguished  contributors  not 
only  for  permitting  me  to  use  their  articles,  but  for  afford- 
ing me  the  pleasure  and  instruction  these  articles  have 
given  me. 

I  am  also  indebted  to  the  editors  of  the  Transactions  of 
the  American  Institute  of  Electrical  Engineers,  the  Jour- 
nal of  Industrial  and  Engineering  Chemistry,  the  Journal 
of  the  Washington  Academy  of  Sciences,  the  Scientific 
Monthly,  Science,  and  the  Journal  of  the  American  Medi- 
cal Association,  for  permission  to  reprint  some  of  these 
articles. 

The  Editor. 


Digitized  by  the  Internet  Archive 

in  2007  with  funding  from 

IVIicrosoft  Corporation 


http://www.archive.org/details/contemporaryscieOOharrrich 


CONTENTS 


FAGK 

Introductiok 9 

Modern  Physics        13 

By  R.  A.  MiLLiKAN 

The  Structure  of  Atoms  and  Its  Bearing  on  Chemical 

Valence 23 

By  Irving  Langmuir 

Engineering  Before  and  After  the  War 34 

By  Sir  Charles  Parsons 

Methods  of  Gas  Warfare 61 

By  S.  J.  M.  Auld,  D.S.M. 

What  Are  Enzymes?         76 

By  Benjamin  Harrow 

Natural  Death  and  the  Duration  of  Life 85 

By  Jacques  Loeb 

The  Physiology  of  the  Aviator 95 

By  Yandell  Henderson 

Twenty- Five   Years   of   Bacteriology:    A   Fragment  of 

Medical  Research 116 

By  Simon  Flexner 

Before  and  After  Lister 152 

By  W.  W.  Keen 

The  Measurement  and  Utilization  of  Brain  Power  in 

THE  Army 192 

By  R.  M.  Yerkes 

Conceptions  and  Misconceptions  in  Psychoanalysis  .     .    211 
By  Trigant  Burrow,  M.D. 

Einstein's  Law  of  Gravitation 230 

By  J.  S.  Ames 

Index 247 


INTRODUCTION  : 

BY 

Benjamin  Harrow 

Associate  in  Physiological  Chemistry, 

Columbia  University 

The  Greeks  were  the  first  to  advance  the  idea  that  mat- 
ter cannot  be  subdivided  indefinitely.  According  to  them  a 
stage  would  be  reached  beyond  which  no  further  subdi- 
vision would  be  possible ;  this  they  called  the  atomic  stage. 

The  Greek  idea  of  atoms  lay  dormant  until  early  in  the 
nineteenth  century,  when  John  Dalton  revived  it.  In  Dal- 
ton's  hands  the  hypothesis  of  atoms  became  the  very  basis 
for  building  the  superstructure  of  chemistry. 

It  may  be  doubted  whether,  with  the  possible  exception 
of  Lavoisier,  any  man  was  more  responsible  for  laying  the 
foundations  of  modern  physics  and  chemistry  than  Dalton, 
native  of  Manchester. 

Not  till  the  latter  part  of  the  last  century  did  the 
rumblings  of  a  storm  make  themselves  heard.  Then 
began  those  celebrated  experiments  on  the  electrical  prop- 
erties of  gases,  by  J.  J.  Thomson  and  others,  followed  by 
Roentgen's  discovery  of  X-rays  and  Madame  Curie's  iso- 
lation of  radium,  which  opened  up  to  view  a  new  conti- 
nent in  science.  For  the  gist  of  these  achievements  was 
to  show  that  the  atom  was  by  no  means  the  smallest  par- 
ticle of  matter ;  that  the  atom,  in  fact,  inconceivably  small 
though  it  be,  was  yet  complex  enough  to  resemble,  in  minia- 

9 


10  CONTEMPORARY  SCIENCE 

ture,  our  solar  system,  with  a  positive  particle  of  electricity 
for  its  sun,  and  negative  particles  (electrons)  to  repre- 
sent the  planets. 

The  more  recent  activities  in  physics  and  chemistry 
have  mainly  focussed  themselves  on  elucidating  the  struc- 
ture of  the  atom.  The  successive  stages  in  the  develop- 
ment of  these  researches  are  summed  up  by  Professor 
Millikan,  the  master  in  the  measurement  of  the  electron. 

The  latest,  and  so  far  the  most  probable,  hypothesis  of 
the  structure  of  the  atom  is  that  due  to  Dr.  Langmuir. 

The  breaking  up  of  the  atom  is  accompanied  by  the 
release  of  enormous  quantities  of  energy.  If  a  catalyzer 
could  be  found  to  accelerate  such  a  reaction,  then  the  solu- 
tion of  the  problem,  the  Energy  of  the  Future,  would  be 
in  sight.  So  far  we  have  not  been  able  either  to  acceler- 
ate or  to  retard  radium  disintegration,  though  Professor 
Rutherford,  of  Cambridge,  has  recently  been  successful  in 
breaking  up  the  nitrogen  into  hydrogen  atoms  by  means 
of  alpha  particles  obtained  from  radium.  Chemists  and 
engineers  are  busy  casting  their  eyes  upon  objects  other 
than  fossiHsed  wood,  because  of  our  prodigal  expenditure 
of  the  coal  resources  of  the  earth.  In  this  connection  Sir 
Charles  Parsons,  English  engineer,  suggests  sources  of 
energy  that  have  so  far  been  neglected. 

Not  without  reason  has  the  Great  War  been  called  the 
Chemists'  War,  yet  there  is  an  element  of  injustice  in  the 
name.  The  layman  assumes,  from  the  activities  of  the 
chemist  during  the  seven  critical  years  from  which  we  are 
emerging,  that  the  function  of  this  type  of  scientist  is  to 
destroy,  just  as  the  function  of  the  physician,  on  the 
other  hand,  is  to  heal.  I  say  this  opinion  of  the  chemist 
is  an  unjust  one.  He  cannot  be  blamed  if  the  weapons  he 
forges  are  misused.  The  several  varieties  of  the  nitro  com- 
pounds that  form  the  series  of  modern  explosives  are  in- 
dispensable in  the  building  of  a  Panama  Canal ;  and  the 
very  gas  that  has  tortured  the  bodies  of  thousands  of  in- 
nocent youngsters  saved  the  lives  of  thousands  during  the 


INTRODUCTION  ii 

late  war  when  applied  in  small  doses  in  somewhat  modi- 
fied form. 

Colonel  Auld's  authoritative  exposition  of  gas  warfare 
is  not  included  to  make  the  reader  as  enthusiastic  about 
this  tool  of  civilized  man  as  it  has  made  a  number  of  gen- 
erals belonging  to  the  five  continents.  The  introduction 
of  "gas"  in  war  has  done  as  much  to  revolutionize  war- 
fare as  the  introduction  of  the  aeroplane.  For  good  or 
for  evil,  gas  warfare  has  come  to  stay,  unless  a  miracle 
happens  and  men  begin  to  use  their  hearts  as  well  as  their 
heads. 

We  can  at  least  point  to  one  constructive  achievement 
indirectly  due  to  the  development  of  gas  warfare.  Sev- 
eral types  of  gas  masks  have  already  been  successfully 
used  by  miners  and  others  as  protection  against  poisonous 
fumes. 

The  physicist  needs  his  mathematics ;  the  chemist  rests 
more  and  more  on  physics ;  and  so  it  is  no  wonder  that  the 
biologist  and  the  medical  man  have  turned  to  physics  and 
chemistry  for  further  inspiration.  Some  of  the  most  not- 
able achievements  in  biology  and  medicine  in  recent  years 
have  been  due  to  the  application  of  the  two  more  funda- 
mental sciences  to  them.  The  elucidation  of  the  nature 
of  enzymes  is  a  case  in  point ;  Professor  Loeb's  and  Pro- 
fessor Henderson's  articles  are  other  and  noteworthy  ex- 
amples. 

Still  it  is  true  to  say  that  in  medicine  the  most  notable 
achievement  so  far  has  been  the  development  of  the  science 
of  bacteriology,  the  foundation  of  which  we  owe  to  the 
chemist  Pasteur.  The  story  of  this  development  is  told 
by  Dr.  Flexner. 

The  chemist  Pasteur  inspired  Lister  the  surgeon;  and 
Dr.  Keen,  who  served  in  the  Civil  as  well  as  in  the  late 
war,  tells  the  story  of  Before  and  After  Lister. 

From  the  physical,  through  the  biological,  to  the  psy- 
chological sciences  is  a  very  natural  evolutionary  process. 
Experimental  psychology,  of  which  psycho-analysis  may 


12  CONTEMPORARY  SCIENCE 

be  considered  a  part,  is  still  in  its  swaddling  clothes ;  but 
the  two  articles  by  Professor  Yerkes  and  Dr.  Burrow  give 
an  idea  of  future  possibilities. 

I  have  put  Professor  Ames's  article  dealing  with  Ein- 
stein's theory  last  on  the  list  because  in  some  ways  it  can 
be  regarded  as  a  summation  or  a  crystallization  of  all  of 
the  sciences.  In  its  conception  of  a  cosmos  decidedly  at 
variance  with  anything  yet  conceived  by  any  school  of 
philosophy,  it  will  attract  the  attention  of  thinking  men  in 
all  countries.  The  scientist  is  immediately  struck  by  the 
way  Einstein  has  utilized  the  various  achievements  in 
physics  and  mathematics  to  build  up  a  coordinated  system 
showing  connecting  links  where  heretofore  none  was  per- 
ceived. The  philosopher  is  equally  fascinated  by  a  theory 
which,  in  detail  extremely  complex,  shows  a  singular 
beauty  of  unity  in  design  when  viewed  as  a  whole.  The 
revolutionary  ideas  propounded  regarding  time  and  space, 
the  brilliant  way  in  which  the  most  universal  property  of 
matter,  gravitation,  is  for  the  first  time  linked  up  with 
other  properties  of  matter,  and  above  all,  the  experimental 
confirmation  of  several  of  his  more  startling  predictions — 
always  the  finest  test  of  scientific  merit — stamp  Einstein 
as  one  of  those  super-men  who  from  time  to  time  are  sent 
to  give  us  a  peep  into  the  beyond. 


MODERN  PHYSICS  . 

(A  lecture  delivered  at  the  Fifth  Midwinter 
Convention  of  the  American  Institute  of  Elec- 
trical  Engineers,    New   York,   Feb.    15,    1917) 

BY 
R.  A.   MiLLIKAN 

Professor  of  Physics,  Chicago  University 

Let  me  run  over  a  list  of  ten  discoveries  which  I  will 
call  the  ten  most  important  advances  [in  physics]  of  the 
last  twenty  years. 

We  may  aptly  characterize  the  physics  of  the  last  twenty 
years  as  the  physics  of  atomism,  and  the  first  discovery 
on  my  list  of  ten  advances  is  the  recent  verification  of  the 
adumbrations  of  the  Greeks  regarding  the  atomic  and  the 
kinetic  theories — the  proof  that,  as  Democritus  had  im- 
agined 500  B.  C,  this  world  does  indeed  consist,  in  every 
part  of  it,  of  matter  which  is  in  violent  motion. 

Up  to  within  six  years  there  were  not  a  few  distin« 
guished  scientists  who  withheld  their  allegiance  even  from 
these  atomic  and  kinetic  theories  of  matter.  The  most 
illustrious  of  them  was  Professor  Wilhelm  Ostwald,  but 
in  the  preface  to  a  new  edition  of  hi^  Outlines  of  Chem- 
istry he  now  says  frankly: 

"I  am  convinced  that  we  have  recently  become  pos- 
sessed of  experimental  evidence  of  the  discreet  or  grained 
nature  of  matter  for  which  the  atomic  hypothesis  sought 
in  vain  for  hundreds  and  thousands  of  years.    The  isola- 

13 


14  CONTEMPORARY  SCIENCE 

tion  and  counting  of  gaseous  ions  on  the  one  hand  .  .  . 
and  on  the  other  the  agreement  of  the  Brownian  move- 
ments with  the  kinetic  hypothesis  .  .  .  justify  the  most 
cautious  scientist  in  now  speaking  of  the  experimental 
proof  of  the  atomic  theory  of  matter.  The  atomic  hy- 
pothesis is  thus  raised  to  the  position  of  scientifically  well- 
founded  theory." 

The  second  advance  is  the  proof  of  the  divisibility  of 
the  atom,  a  proof  which  grew  out  of  the  discovery^  of 
X-rays.  Let  me  tell  you  how.  If  you  have  here  two 
plates  with  an  electric  field  between  them,  and  nothing 
else  but  a  monatomic  gas  like  helium,  then  it  is  found  that 
when  the  field  is  thrown  on,  the  helium  is  perfectly  stag- 
nant; but  when  a  beam  of  X-rays  is  shot  between  the 
plates,  some  of  the  molecules  become  electrically  charged 
and  begin  to  jump, — some  toward  the  upper,  and  some 
toward  the  lower  plate,  where  their  presence  can  be  de- 
tected by  an  electrical  measuring  instrument.  What  does 
that  show?  It  shows  that  the  thing  which  we  call  an 
atom  has  electrical  charges  as  its  constituents;  and  the 
history  of  the  last  twenty  years  in  physics  has  consisted 
pretty  largely  in  determining  what  are  the  properties  of 
these  electrical  constituents. 

The  third  is  the  discovery  of  radio-activity,  which  oc- 
curred just  a  little  after  the  discovery  of  X-rays.  And 
here  again  we  found  matter  doing  things  we  had  never 
dreamed  it  was  doing;  vis,  shooting  off  from  itself  both 
negatively  and  positively  charged  particles,  the  negatives 
with  a  speed  which  may  approach  close  to  the  velocity  of 
light,  186,000  miles  per  second,  and  the  positives  with  a 
speed  of  one-tenth  of  that,  or  18,000  miles.  The  fact  that 
such  speeds  could  be  imparted  to  projectiles  of  any  kind 
was  undreamed  of  twenty  years  ago. 

The  fourth  discovery  that  I  wish  to  mention  is  the  dis- 
covery of  the  atomicity  of  electricity, — the  proof  that  the 
thing  we  call  electricity  is  built  up  out  of  a  definite  num- 
ber of  specks  of  electricity,  all  exactly  alike;  and  that 


MODERN  PHYSICS  15 

what  we  call  an  electrical  current  consists  simply  in  the 
journey  along"  the  conductor  of  these  electrical  specks, 
which  we  may  call  with  perfect  justice  definite  material 
bodies.  Now,  I  can  give  you  in  just  a  word  the  proof  of 
that  statement.  There  are  half  a  dozen  ways  in  which  it 
could  be  approached.  I  will  mention  the  one  with  which 
I  am  most  familiar,  because  it  is  the  particular  proof  which 
we  worked  out  in  our  laboratory. 

We  took  these  plates  with  a  field  of  10,000  volts  be- 
tween them,  with  a  little  hole  in  the  top  plate,  and  blew 
an  oil  spray  above  the  top  plate  so  as  to  get  an  electrically 
charged  body  just  as  small  as  we  could ;  for  we  expected 
that  the  frictional  process  involved  in  blowing  the  spray 
would  charge  the  drops ;  and  this,  indeed,  it  was  found  to 
do.  We  let  one  of  those  drops  come  into  the  space  be- 
tween the  plates,  and  then  moved  it  up  and  down  by  an 
electrical  field,  throwing  it  on  the  field  as  it  came  close  to 
the  bottom  plate,  and  throwing  it  of?  as  it  approached  the 
upper  one.  And  so  we  kept  that  oil  drop  going  up  and 
down  between  the  plates,  in  the  hope  that  it  would  capture 
some  of  the  ions  which  we  knew  existed  in  the  air,  put 
there  by  radium  or  other  agencies.  The  drop  met  our 
fullest  expectations.  It  captured  ions  frequently  and  sig- 
nalled the  fact  of  each  capture  to  the  observer  by  the 
change  in  its  speed  in  the  field.  For  the  oil  drop  is  an 
electrically  charged  body,  and  in  a  given  field  it  moves 
with  a  definite  speed.  If,  however,  it  captures  an  ion, 
its  charge  increases  or  decreases,  and  hence  its  speed  in- 
creases or  decreases.  If  the  charges  on  ions  are  all  alike, 
then  we  can  only  get  one  particular  change  in  speed.  If 
the  charge  that  is  already  upon  it,  put  there  by  the  fric- 
tional process,  is  built  up  out  of  these  same  units,  then 
the  total  speed  which  the  field  will  impart  must  be  an 
exact  multiple  of  the  change  in  speed  which  the  capture 
of  an  ion  produces.  In  other  words,  if  electricity  is  atomic 
in  structure,  you  cannot  get  in  a  given  field  anything  ex- 
cept a  definite  number  of  speeds,  which  will  make  an  arith- 


i6  CONTEMPORARY  SCIENCE 

metical  series ;  that  is,  which  will  come  up  by  steps, — one, 
two,  three,  etc.  That  is  exactly  what  we  found.  We 
have  experimented  with  thousands  of  drops  and  scores  of 
different  substances,  and  they  always  work  exactly  that 
way.  Both  positively  and  negatively  charged  drops  are 
found  to  act  in  quite  the  same  way,  showing  that  both 
positive  and  negative  electrical  charges  are  built  up  of 
specks  of  electricity.  Further  we  can  count  the  number 
of  those  specks,  which  we  will  call  electrons,  in  a  given 
drop,  with  the  same  certainty  with  which  you  can  count 
the  number  of  fingers  that  are  on  your  hand.  And 
again  since  Rowland  showed  that  an  electrical  current  is 
nothing  but  a  charge  in  motion,  you  have  here  the  proof 
that  the  electrical  current  that  goes  through  these  lamps, 
for  example,  is  nothing  except  the  motion  of  a  certain 
number  of  electrical  specks  through  or  over  the  filament 
of  the  lamp.  Add  to  that  J.  J.  Thomson's  discovery  made 
in  1881,  that  an  electrical  charge  possesses  inertia,  the 
only  distinguishing  property  of  matter,  and  you  have  made 
it  perfectly  legitimate  to  say  that  an  electrical  current  in 
a  wire  is  a  definite,  material,  granular  something  which 
is  moving  along  that  wire. 

The  fifth  great  discovery  of  modern  physics  is  the  bring- 
ing forward  of  evidence  for  the  electrical  origin  of  mass. 
I  have  just  said  that  electricity  is  material.  Can  we  turn 
it  around,  and  say  that  all  matter  is  electrical  in  origin? 
The  last  is  not  exactly  the  same  as  the  first,  and  it  needs 
evidence.  When  we  have  proved  that  an  electrical  charge 
possesses  inertia  or  mass  we  have  not  shown  that  there  is 
no  inertia  in  matter  which  is  not  electrical  in  its  origin. 
Now  we  have  a  certain  amount  of  evidence  upon  this  point 
and  I  wish  to  state  what  that  evidence  is.  We  can  meas- 
ure the  inertia  of  the  negative  electron  and  it  is  found  to 
be  one-one  thousand  eight  hundred  and  forty-fifth  part  of 
the  inertia  of  a  hydrogen  atom,  but  the  positive  electron  is 
never  found  with  an  inertia  less  than  the  inertia  of  a  hy- 
drogen atom.     Let  us  consider  the  inertia  of  the  negative. 


MODERN  PHYSICS  17 

So  long  as  it  is  moving*  slowly  compared  with  the  speed 
of  light  its  inertia  remains  constant  because  the  shape  of 
its  electromagnetic  field  is  not  appreciably  distorted  by  its 
motion.  But  as  soon  as  you  imagine  it  to  be  moving  with 
a  speed  which  is  close  to  the  speed  of  light,  that  is  with  a 
speed  which  is  nearly  as  great  as  the  speed  with  which  its 
own  electro  magnetic  field  can  travel  forward,  then  fur- 
ther change  in  speed  will  distort  the  field  and  hence  change 
the  inertia.  In  other  words,  the  inertia  of  a  charge  ought 
to  be  a  function  of  speed  only  when  the  speed  approaches 
the  speed  of  light.  As  a  matter  of  fact,  when  it  is  from 
0.1  up  to  0.9  of  the  speed  of  light,  you  can  compute  just 
how  it  ought  to  vary.  Now,  by  some  happy  chance  the 
physicist  has  found  negative  electrons,  namely  those  shot 
off  by  radium,  which  are  going  with  these  speeds,  and 
hence  it  is  possible  to  test  our  theory  for  these  particles 
and  see  whether  the  rate  of  change  of  their  inertia  with 
the  speed  checks  with  the  theoretical  value.  It  is  found 
that  there  is  such  a  check.  This  means  that  there  isn't 
any  inertia  in  those  particles  which  does  not  obey  the  elec- 
tromagnetic laws.  Therefore,  we  have  good  reason  for 
assuming  that  the  negative  electron  is  nothing  hut  a  dis-^ 
embodied  electrical  charge,  and  that  its  inertia  is  wholly 
of  electrical  origin. 

With  respect  to  the  positive  electron,  we  have  not  such 
convincing  evidence  as  yet,  but  it  is  obviously  in  the  in- 
terest of  simplicity  to  assume  one  kind  of  inertia  rather 
than  two  kinds.  Further,  we  have  a  little  bit  of  evidence 
of  this  kind,  and  I  wish  to  mention  what  it  is,  because  that 
will  furnish  an  introduction  to  my  sixth  important  mod- 
ern discovery.  We  have  good  reasons  for  thinking  that 
there  is  only  one  positive  electron  in  the  hydrogen  atom, 
but  that  the  mass,  or  inertia  of  that  positive  is  almost  the 
mass  of  the  hydrogen  atom — at  any  rate  we  never  find  it 
any  less.  If  this  inertia  is  all  electrical^  then  we  know 
from  theory  that  the  charge  must  be  more  condensed  in 
the  positive  than  in  the  negative ;  consequently,  if  we  are 


i8  CONTEMPORARY  SCIENCE 

going  to.  make  the  observed  inertia  of  the  hydrogen  nu- 
cleus all  electrical,  it  must  possess  an  even  denser  charge 
than  that  on  the  negative. 

This  brings  me  to  the  sixth  of  our  discoveries,  namely 
the  discovery  of  the  nucleus  atom.  Let  me  give  you  just 
a  brief  statement  of  how  we  know  that  the  atom  is  some- 
what like  a  miniature  solar  system,  with  an  extraordinarily 
minute  nucleus,  the  size  of  which  is  never  more  than  one- 
one  hundred  thousandth  part  of  the  diameter  of  the  atom 
— and  with  a  certain  number  of  subsidiary  bodies — nega- 
tive electrons — which  we  may  liken  to  the  planets,  and 
which  are  somewhere  around  the  outside.  How  do  we 
know  that  is  the  case?  We  have  this  direct  evidence. 
Nature  takes  a  helium  atom  which  is  going  with  a  speed 
of  18,000  miles  per  second,  and  Nature  shoots  that  atom 
right  through  a  glass  wall  without  leaving  any  hole  behind, 
and  without  in  any  way  interferring  with  the  structure  of 
the  molecules  of  the  glass.  I  can  show  you  photographs 
that  make  the  thing  so  clear  that  the  man  in  the  street  can 
see  it.  This  obviously  means  that  the  positive  nucleus 
itself  mu'st  be  extraordinarily  minute.  Indeed  the  fact 
that  the  negative  electron  actually  shoots  through  those 
hundreds  of  thousands  of  atoms  without  ever  going  near 
enough  to  any  constituent  of  those  atoms  to  knock  any 
one  of  them  out,  and  the  fact  that  the  positive  nucleus  of 
helium,  viz.,  the  alpha  particle,  shoots  through  even  more 
molecules  without  being  deflected  at  all  from  its  course, 
causes  one  to  wonder  whether  there  is  anything  at  all  that 
is  impenetrable  in  the  atom.  Why  do  we  say  there  is  a 
nucleus  there?  Because  direct  experiment  says  there  is. 
There  is  a  certain  portion  of  the  atom  which  the  alpha 
particle  itself  cannot  penetrate.  If  the  impact  is  head 
on,  the  alpha  particle  goes  right  up  to  the  atom  and  then 
it  backs  out  again.  Or  if  it  comes  up  to  the  atom  at  an 
angle,  it  glances  off  that  way.  Rutherford,  Geiger  and 
Marsden  counted  the  percentage  of  alpha  particles  which 
go   straight   on,   and  the  percentage   which   go   off  at  a 


MODERN  PHYSICS  19 

tangent ;  and  in  this  manner  we  find  how  big-  that  nucleus 
is.  By  the  size  of  the  nucleus  I  mean  the  size  of  that 
portion  of  the  atom  which  is  impenetrable  to  the  alpha 
particles.  It  amounts  to  about  10-13,000,000,000,000  cen- 
timeters. The  diameter  of  the  atom  is  lO"^.  Furthermore, 
by  counting  how  the  deflections  of  the  alpha  particles  are 
distributed  around  this  sphere,  which  we  can  do  directly 
with  the  aid  of  zinc  sulphide  ^spread  over  the  inside  of 
the  sphere,  we  can  obtain  the  number  of  alpha  particles 
deflected  through  any  given  angle.  With  a  little  analysis 
of  unquestionable  correctness,  we  find  how  many  unit 
charges, — positive  electrons, — there  are  in  this  exceedingly 
small  nucleus,  and  it  comes  out  approximately  to  one-half 
of  the  atomic  weight. 

I  now  come  to  another  extraordinary  discovery.  This 
one  does  not  merely  tell  us  approximately  how  many  elec- 
trons there  are  in  the  nucleus  but  it  tells  us  exactly  how 
many  there  are,  and  the  result  checks  with  the  number 
obtained  by  the  foregoing  approximate  method.  This 
brings  me  to  the  recent  discoveries  in  the  field  of  X-rays, 
and  I  will  call  the  seventh  of  the  modern  advances  the 
discovery  of  the  nature  of  X-rays,  which  was  virtually 
made  by  Barkla  in  1904.  For  Barkla  and  others  had 
proved  that  there  are  two  types  of  X-rays :  first.  X-rays 
which  consist  in  simple  ether  pulses  pushed  off  from  an 
electron  when  it  changes  its  speed ;  and  second,  so-called 
characteristic  X-rays.  When  the  electrons  bump  into  a 
target  they  set  something  in  the  target  into  vibration,  and 
this  something  sends  off  perfectly  definite  characteristic 
X-rays,  which  are  like  monochromatic  light.  So  that  we 
have  two  types  of  X-rays, — pulse  X-rays,  like  white  light ; 
and  monochromatic  X-rays,  like  monochromatic  light 
(such  as  mercury  gives  rise  to).  That  is  the  seventh  of 
our  great  modern  discoveries,  and  it  must  be  credited 
chiefly  to  Barkla. 

The  eighth  I  will  call  the  discovery  of  crystal  structure 
by  the  study  of  X-rays,  which  is  due  to  Laue  in  Munich, 


20  CONTEMPORARY  SCIENCE 

and  Bragg,  in  England.  The  method  is  simply  this.  We 
analyze  light  by  a  grating  which  consists  of  a  series  of 
equally  spaced  lines  on  a  reflecting  or  transmitting  sur- 
face. With  such  a  device  we  can  split  light  up  into  a 
spectrum ;  but  we  cannot  do  this  unless  the  width  of  the 
grating  space  is  comparable  with  the  wave  length  of  the 
light.  In  the  case  of  X-rays,  we  had  no  knowledge  of 
gratings  whose  grating  spaces  were  anything  like  as  small 
as  the  wave  length  of  X-rays.  In  fact  such  gratings  were 
unknown  until  Laue  had  the  bright  idea  of  using  the  regu- 
lar arrangement  of  the  atoms  in  a  crystal  for  a  grating  to 
see  whether  that  would  not  do  the  work,  and  it  did  the 
work  marvelously  well.  It  was  found  that  we  could  com- 
pute the  grating  space  of  certain  crystals  from  the  density 
and  the  atomic  weight,  and  then  from  the  observed  spec- 
trum find  the  wave  length  of  X-rays.  And  now  knowing 
the  wave  length  we  can  work  backward  and  find  the  grat- 
ing-space for  other  crystals.  We  are  now  using  this 
method  for  finding  the  positions  and  the  arrangements  of 
the  atoms  in  crystalline  bodies.  Prof.  Bragg  in  his  recent 
book  on  X-rays  and  crystal  structure  has  described  this 
work  very  beautifully.  Thus  a  whole  new  field  of  ex- 
perimentation has  been  opened  up  and  is  being  pursued 
in  a  great  many  laboratories,  and  with  particular  success 
by  A.  W.  Hull  at  the  laboratory  of  the  General  Electric 
Company.  There  are  almost  unlimited  possibilities  for 
the  chemist  in  the  discovery  of  the  exact  position  of  the 
atoms  in  any  kind  of  crystal  by  this  method. 

But  the  results  of  this  discovery  as  of  most  of  the  others 
which  I  have  mentioned  are  rather  insignificant  when  com- 
pared with  those  of  the  ninth  which  I  am  going  to  men- 
tion, namely  the  discovery  of  the  relations  between  the 
elements,  and  the  extension  of  our  knowledge  of  the  radi- 
ations emitted  by  different  substances.  This  discovery 
was  made  by  a  young  Englishman,  Moseley,  only  twenty- 
six  years  old,  who  has  already,  unfortunately,  fallen  a 
victim  to  this  juggernaut  which  is  at  the  present  time 


MODERN  PHYSICS  21 

crushing  out  the  finest  scientific  brains  in  the  world.  Mosc: 
ley  was  killed  at  the  age  of  twenty-seven,  a  year  after  h^ 
had  made  his  epoch-making  discovery,  and  all  the  live^ 
and  all  the  interests  of  the  eternally  infamous  men  who 
made  this  war  are  not  to  be  compared  in  value  to  the  world 
with  a  hair  of  Moseley's  head.  Yet  he  had  to  be  sacri- 
ficed to  save  a  threatened  civilization.  A  double  honor  to 
Moseley. 

His  discovery  was  this :  He  was  analyzing  the  charac- 
teristic X-rays  which  are  given  off  when  any  kind  of  a 
substance  is  bombarded  with  cathode  rays.  The  experi- 
ment was  in  my  judgment  as  brilliantly  conceived,  as  care- 
fully and  skillfully  carried  out,  and  as  illuminating  in  its 
results,  as  any  which  has  been  done  in  the  last  fifty  years. 
What  he  found  was  this,  that  the  atoms  of  all  the  different 
substances  emit  radiations  or  groups  of  radiations  which 
are  extraordinarily  similar,  but  that  these  radiations  differ 
in  their  wave  lengths  as  we  go  from  substance  to  sub- 
stance. The  whole  discovery  can  be  stated  in  this  fashion : 
If  you  take  the  highest  frequency  emitted  by  a  given  atom, 
and  if  you  lay  down  on  a  table  a  length  which  is  equal  to 
the  square  root  of  this  frequency,  and  if  on  top  of  that 
you  lay  down  the  square  root  of  the  frequency  of  the 
atom  which  has  the  next  lower  frequency,  and  so  if  you 
continue  to  lay  down,  with  one  group  of  ends  together, 
the  measured  square  root  frequencies  of  all  the  elements 
that  you  can  study,  then  what  have  you  got?  You  find 
that  you  have  a  flight  of  stairs,  with  perfectly  definite 
equal  treads;  that  is,  the  frequencies  change  by  definite 
steps  as  you  go  from  element  to  element.  And  there  are 
only  four  vacant  treads  between  the  lightest  element  which 
Moseley  could  study,  namely  aluminum  and  the  heaviest 
one,  namely  lead ;  thus  indicating  that  there  are  only  four 
elements  in  this  range  which  we  have  not  already  found. 

We  may  then  picture  with  considerable  confidence  this 
whole  physical  world  as  built  up  out  of  one  positive  and 
one  negative  electron.     The  positive  electron  is  the  nu- 


22  CONTEMPORARY  SCIENCE 

cleus  of  the  hydrogen  atom.  It  is  very  minute  in  com- 
parison with  the  negative,  but  much  more  massive.  When 
two  free  positive  electrons  are  tied  together  we  have  the 
heHum  atom.  We  don't  know  why  these  positives  cling 
together. 

My  last  of  the  great  discoveries  of  modern  physics  is 
one  that  I  will  just  touch  upon.  It  is  the  discovery  of 
quantum  relations  in  photo-electricity,  in  X-rays,  and  in 
optical  spectra ;  but  here  I  am  coming  to  a  field  which  we 
do  not  know  very  much  about,  which  we  do  not  yet  under- 
stand, and  my  main  motive  in  introducing  it  is  to  convince 
you  that  the  physicist,  in  spite  of  all  he  knows,  or  thinks 
he  knows,  is  a  fairly  modest  fellow;  because  there  are 
some  things  he  knows  he  doesn't  know,  and  one  at  present 
is  the  nature  of  radiation.  However,  we  know  some  things 
about  it  that  are  new.  For  example,  it  is  an  extraor- 
dinarily interesting  fact  that  when  light  of  the  X-ray  type, 
or  indeed,  light  of  any  frequency  falls  upon  say  a  lithium 
or  sodium  surface,  or  upon  almost  any  surface,  it  has  the 
property  in  some  way  of  taking  hold  of  a  negative  electron 
in  the  atoms  of  that  surface  and  of  hurling  that  electron 
out  with  a  speed  which  can  be  measured,  and  which  we 
find  to  be  exactly  proportional  to  the  frequency  of  the 
light.  That  is  an  extraordinary  phenomenon,  and  it  is 
one  that  we  explain  on  a  kind  of  quantum  theory  which 
I  will  not  attempt  to  go  into  here,  because  of  the  fact  that 
we  have  not  yet  worked  it  out  fully ;  but  at  any  rate,  the 
quantum  constant  comes  out  of  the  photo-electric  effect, 
as  shown  in  my  own  work,  out  of  X-ray  work  as  discov- 
ered by  Duane  and  Hunt  at  Harvard,  and  out  of  spectro- 
scope work,  as  shown  by  Bohr  in  the  beautiful  theory  of 
the  atom  which  he  has  developed  within  the  last  three  or 
four  years. 


THE   STRUCTURE   OF  ATOMS   AND   ITS 
BEARING  ON  CHEMICAL  VALENCE 

BY 

Irving  Langmuir 
General  Electric  Company 

According  to  the  well-established  Rutherford-Bohr 
theory,  all  the  positive  electricity  in  an  atom  is  concen- 
trated in  a  nucleus  at  its  center.  The  dimensions  of  this 
nucleus  are  negligibly  small  compared  with  those  of  the 
rest  of  the  atom,  its  diameter  being  of  the  order  of  o.ooool 
of  that  of  the  atom.  The  charge  on  the  nucleus  is  an  inte- 
gral multiple  of  the  charge  of  an  electron  but  of  course 
opposite  in  sign.  The  remainder  of  the  atom  consists  of 
electrons  arranged  in  space  about  the  nucleus,  the  normal 
number  of  such  electrons  (called  the  atomic  number) 
being  equal  to  the  number  of  unit  positive  charges  on  the 
nucleus,  so  that  the  atom  as  a  whole  is  electrically  neutral. 
If  the  number  of  electrons  in  the  atom  exceeds  the  atomic 
number  we  have  a  negatively  charged  atom  or  ion  while 
in  the  reverse  case  a  positively  charged  atom  or  ion  re- 
sults. The  atomic  number  of  any  element  has  been  found 
to  be  equal  to  the  ordinal  number  of  the  element  in  the 
periodic  table.  Thus  hydrogen  has  the  atomic  number 
one,  helium  2,  lithium  3,  carbon  6,  neon  10,  chlorine  17, 
nickel  28,  silver  47,  cerium,  58,  tungsten  74,  radium  88, 
and  uranium  92.     The  atomic  numbers  can  be  determined 

23 


^4  CONTEMPORARY  SCIENCE 

experimentally  from  the  X-ray  spectrum  so  that  we  are 
not  dependent  upon  the  periodic  table  for  our  knowledge 
of  these  numbers. 

Bohr,  Sommerfeld  and  others  have  developed  an  exten- 
sive and  very  successful  theory  of  spectra  upon  the  hypo- 
thesis that  the  electrons  in  atoms  are  in  rapid  rotation  in 
plane  orbits  about  the  nucleus  in  much  the  same  way  as 
the  planets  revolve  around  the  sun.  Stark,  Parson,  and 
G.  N.  Lewis  on  the  other  hand,  starting  from  chemical 
evidence,  have  assumed  that  the  electrons  are  stationary 
in  position.  It  should  be  noted  that  Bohr's  theory  has  had 
its  greatest  success  when  applied  to  atoms  or  ions  contain- 
ing only  one  electron  and  that  it  seems  incapable  of  ex- 
plaining the  chemical  or  ordinary  physical  properties  of 
even  such  simple  elements  as  lithium,  carbon,  or  neon. 

The  two  theories  can,  however,  be  reconciled  if  we  con- 
sider that  the  electrons,  as  a  result  of  forces  which  they 
exert  on  one  another,  rotate  about  certain  definite  posi- 
tions in  the  atom  which  are  distributed  symmetrically  in 
three  dimensions.  Thus  for  atoms  containing  only  a 
single  electron  the  chemical  theory  is  in  agreement  with 
Bohr's  theory.  But  for  an  atom  such  as  neon  the  eight 
electrons  in  the  outside  layer  would  revolve  around  posi- 
tions which  are  located  about  the  nucleus  in  the  same 
way  that  the  eight  corners  of  a  cube  are  arranged  about 
the  center  of  the  cube.  This  structure  is  not  inconsistent 
with  those  parts  of  Bohr's  theory  which  have  received  ex- 
perimental confirmation.  In  fact,  Born  and  Lande,^ 
starting  from  Bohr's  theory  and  without  knowledge  of 
Lewis'  work,  arrived  at  exactly  this  conception  of  the 
structure  of  atoms  (i.e.,  the  cubic  atom)  from  a  study  of 
the  compressibility  of  the  salts  of  the  alkali  metals. 

The  atomic  numbers  and  the  properties  of  the  inert 
gases  furnish  us  with  a  clue  to  the  arrangement  of  the 
electrons  within  atoms.    The  low  boiling  point,  the  high 

^Verh.  d.  phys.  Ges.,  20  (1918),  210. 


THE  STRUCTURE  OF  ATOMS  25 

ionizing  potential,  the  chemical  inertness,  etc.,  of  helium 
prove  that  the  arrangement  of  the  electrons  in  the  helium 
atom  is  more  stable  than  that  in  any  other  atom.  Since 
this  atom  contains  two  electrons  we  must  conclude  that  a 
pair  of  electrons  in  the  presence  of  a  nucleus  represents  a 
very  stable  group.  It  is  reasonable  that  with  elements 
of  higher  atomic  number  there  should  be  an  even  greater 
tendency  for  this  stable  pair  of  electrons  to  form  about 
the  nucleus.  There  are  two  sets  of  facts  which  furnish 
conclusive  experimental  evidence  that  this  stable  pair  ex- 
ists in  all  atoms  above  helium. 

In  the  first  place,  the  properties  of  lithium,  beryllium, 
etc.,  show  that  in  these  elements  also  the  first  two  electrons 
are  held  firmly  while  the  remainder  are  easily  detached. 
Thus,  lithium  readily  forms  a  univalent  positive  ion  by 
the  detachment  of  one  of  the  three  electrons  in  its  neutral 
atom.  The  divalence  and  other  properties  of  beryllium 
prove  that  there  is  little  or  no  tendency  for  a  second  stable 
pair  of  electrons  to  surround  the  first  pair. 

In  the  second  place,  the  absence  of  irregularities  in  the 
observed  K  and  L  series  of  the  X-ray  spectra  of  the  vari- 
ous elements  proves  that  there  are  no  sudden  changes  in 
the  number  of  electrons  in  the  innermost  layers  of  elec- 
trons about  the  nucleus.  From  these  two  sets  of  facts, 
as  well  as  from  other  evidence,  we  may  take  it  as  a  fun- 
damental principle  that  the  arrangement  of  the  inner  elec- 
trons undergoes  no  change  as  we  pass  from  elements  of 
smaller  to  those  of  higher  atomic  number. 

The  properties  of  neon  indicate  that  its  atoms  are  more 
stable  than  those  of  any  other  element  except  helium. 
Since  the  atomic  number  is  10,  and  the  first  2  electrons 
form  a  stable  pair  about  the  nucleus  as  in  the  helium  atom, 
it  follows  directly  that  the  other  eight  electrons  arrange 
themselves  in  a  second  layer  or  shell  possessing  a  very 
high  stability.  If  these  8  electrons  revolved  about  the 
nucleus  in  a  single  circular  orbit  or  ring,  as  would  be  sug- 
gested by  Bohr's  theory,  there  is  no  apparent  reason  why 


26  CONTEMPORARY  SCIENCE 

there  should  be  any  very  great  difference  in  stability  be- 
tween rings  having  7,  8  or  9  electrons.  On  the  other  hand, 
we  readily  see  that  the  geometrical  symmetry  of  the  ar- 
rangement of  the  8  electrons  at  (or  rotating  about)  the 
8  corners  of  a  cube  would  not  only  account  for  a  high 
degree  of  stability  but  for  the  fact  that  an  arrangement  of 
7  or  9  electrons  would  have  no  such  stability.  Chemical 
considerations  and  Born  and  Lande's  work  on  compressi- 
bility also  lead  us  to  this  spatial  arrangement  of  the  elec- 
trons. We  shall  refer  to  the  stable  group  of  8  electrons 
by  the  term  octet.  From  the  principles  already  enunci- 
ated it  is  clear  that  in  the  atoms  of  all  the  elements  above 
neon  the  inner  electrons  are  arranged  in  the  same  way  as 
those  of  neon. 

From  the  atomic  numbers  of  the  inert  gases  we  are  thus 
able  to  determine  the  number  of  electrons  in  the  various 
layers  or  shells  of  electrons  which  exist  in  the  atoms.  The 
results  are  summarized  in  Table  I. 

Table  I — Distribution  of  Electrons  in  the  Various  Shells 

Inert    Gas 

Number  of  Corresponding  to 

Shell  Electrons  Completed  Layer 

1st  shell    2  =  2X12  He    2 

2nd   shell,   1st  layer 8  =  2X22  Ne   10 

2nd  shell,  2nd  layer 8  =  2X22  Ar   18 

3rd  shell,  1st  layer 18  =  2X32  Kr   36 

3rd  shell,  2nd  layer 18  =  2  X  32  Xe   54 

4th   shell,    1st   layer 32  =  2X42  Nt   86 

Thus  the  xenon  atom  with  an  atomic  number  54  contains 
54  electrons  arranged  as  follows:  Close  to  the  nucleus 
are  two  electrons  which  constitute  the  first  shell.  This 
is  surrounded  by  the  second  shell  which  contains  two 
^'layers"  of  8  electrons  each.  The  third  shell,  which  in 
the  xenon  atom  is  the  outside  shell,  contains  18  electrons. 

An  examination  of  the  number  of  electrons  in  the  layers 
(Table  I,  2nd  column)   shows  that  they  bear  a  simple 


THE  STRUCTURE  OF  ATOMS  27 

mathematical  relation  to  each  other,  namely,  that  they  are 
proportional  to  the  squares  of  the  successive  integers  i,  2, 
3,  and  4.  This  is  to  be  looked  upon  as  perhaps  the  most 
fundamental  fact  underlying  the  periodic  arrangement  of 
the  elements.  It  is  significant  that  in  Bohr's  theory  these 
same  numbers,  i,  4,  9,  16,  etc.,  play  a  prominent  part. 
Thus  the  energies  of  the  electron  in  the  various  "station- 
ary states"  are  proportional  to  one,  one-quarter,  one-ninth, 
one-sixteenth,  etc.,  and  the  diameters  of  the  various  pos- 
sible orbits  in  Bohr's  theory  are  proportional  to  i,  4,  9, 
16,  etc.  In  Bohr's  theory  the  various  stationary  states 
correspond  to  different  number  of  quanta  (Planck's  quan- 
tum theory),  the  innermost  orbit  corresponding  to  one 
quantum,  the  second  orbit  to  two  quanta,  etc.  We  should 
thus  consider  (Table  I)  that  the  electrons  in  the  ist  shell 
are  monoquantic,  those  in  both  layers  of  the  2nd  shell  are 
diquantic,  etc.  It  is  interesting  that  Born  and  Lande  from 
quite  other  evidence  have  concluded  that  the  outermost 
electrons  of  the  chlorine  atom  (2nd  layer  of  the  2nd  shell) 
are  diquantic  instead  of  triquantic  as  was  at  first  assumed. 

The  foregoing  theory  of  the  arrangement  of  electrons 
in  atoms  explains  the  general  features  of  the  entire  peri- 
odic system  of  the  elements  and  is  particularly  successful 
in  accounting  for  the  position  and  the  properties  of  the 
so-called  8th  group  and  the  rare  earth  elements.  It  also 
serves  to  correlate  the  magnetic  properties  of  the  elements. 

Let  us  now  consider  the  bearing  of  this  theory  of  atomic 
structure  on  the  phenomena  of  chemical  valence.  The  out- 
standing feature  of  the  theory  is  that  there  are  certain 
groups  of  electrons,  such  as  the  pair  in  the  first  shell  and 
the  octet  in  the  second,  that  have  a  remarkable  stability. 
Those  atoms  in  which  all  the  electrons  form  parts  of  such 
stable  groups  (vk.,  the  inert  gases)  will  have  no  tendency 
to  change  the  arrangement  of  their  electrons  and  will  thus 
not  undergo  chemical  change.  Suppose,  however,  we 
bring  together  an  atom  of  fluorine  (N  =  91)^  and  an  atom 

1  We  will  denote  the  atomic  number  of  an  element  by  N. 


28  CONTEMPORARY  SCIENCE 

of  sodium  (N  =  ii).  Ten  electrons  are  needed  for  the 
stable  pair  in  the  first  shell  and  the  octet  in  the 
second  shell,  as  in  the  neon  atom.  The  sodium  atom 
has  one  more  electron  than  is  needed  to  give  this 
stable  structure  while  the  fluorine  atom  has  one  electron 
too  few.  It  is  obvious  then  that  the  extra  electron  of  the 
sodium  atom  should  pass  over  completely  to  the  fluorine 
atom.  This  leaves  the  sodium  atom  with  a  single  positive 
charge  while  the  fluorine  becomes  negatively  charged.  If 
the  two  charged  atoms  or  ions  ^  were  alone  in  space  they 
would  be  drawn  together  by  the  electrostatic  force  and 
would  move  as  a  unit  and  thus  constitute  a  molecule.  How- 
ever, if  other  sodium  and  fluorine  ions  are  brought  into 
contact  with  the  "molecule"  they  will  be  attracted  as  well 
as  the  first  one  was.  There  will  result  (at  not  too  high 
temperature)  a  space  lattice  consisting  of  alternate  positive 
and  negative  ions  and  the  "molecule"  of  sodium  fluoride 
will  have  disappeared.  Now  this  is  just  the  structure 
which  we  find  experimentally  for  sodium  fluoride  by 
Bragg's  method  of  X-ray  crystal  analysis.  There  are  no 
bonds  linking  individual  pairs  of  atoms  together.  The 
salt  is  an  electrolytic  conductor  only  in  so  far  as  its  ions 
are  free  to  move.  In  the  molten  condition  or  when  dis- 
solved in  water,  therefore,  it  becomes  a  good  con- 
ductor. 

The  case  of  magnesium  (N  =  12)  and  oxygen  (N  =  8) 
is  similar  except  that  two  electrons  are  transferred  from 
the  magnesium  to  the  oxygen  atom.     The  resulting  ions 

2  It  is  convenient  and  it  has  been  customary  with  many  physi- 
cists to  speak  of  a  charged  atom  or  molecule  as  an  ion,  irre- 
spective of  whether  or  not  the  particle  is  able  to  wander  under 
the  influence  of  an  electric  field.  The  writer  has  used  the  term 
in  this  way  in  his  recent  publications.  This  practice  is  very  dis- 
tasteful to  many  physical  chemists  and  is  likely  to  be  misunder- 
stood by  them.  Nevertheless,  it  seems  to  me  probable,  especially 
in  view  of  the  recent  work  of  Milner  and  Ghosh,  that  it  will  be 
desirable  to  abandon  the  physical  chemists'  definition  of  the  ion 
and  to  apply  it  to  all  charged  atoms  or  molecules.  The  ion 
which  wanders  may  then  be  referred  to  as  a  "free  ion." 


THE  STRUCTURE  OF  ATOMS  29 

have  their  electrons  arranged  exactly  like  those  of  the  neon 
atoms  and  the  ions  of  sodium  and  fluorine.  Therefore, 
the  crystalline  form  of  magnesium  oxide  and  sodium  flu- 
oride should  be  identical,  and  this  prediction  of  the  theory 
has  been  confirmed  experimentally  by  Dr.  A.  W.  Hull  by 
the  X-ray  method.  Because  of  the  much  greater  forces 
acting  between  the  ions  as  a  result  of  the  double  charges, 
the  stability  of  the  magnesium  oxide  is  much  higher  than 
that  of  the  sodium  fluoride.  This  is  manifested  by  the 
high  melting  point,  low  conductivity,  low  solubility,  and 
hardness  of  magnesium  oxide. 

Phosphorus  (N  =  is)  and  sulfur  (N  =  16)  have,  re- 
spectively, 5  and  6  electrons  more  than  neon,  and  are  thus 
capable  of  giving  up  these  numbers  of  electrons.  If  these 
elements  are  brought  into  contact  with  an  excess  of  fluor- 
ine (which  because  of  its  proximity  to  neon  has  a  par- 
ticularly strong  tendency  to  take  electrons)  all  the  extra 
electrons  pass  to  fluorine  atoms.  Thus  a  sulfur  atom  will 
supply  electrons  to  6  fluorine  atoms  and  will  form  the 
compound  SFq.  The  force  acting  between  the  fluorine 
ions  and  the  central  sulfur  ion  is  still  electrostatic  in  na- 
ture but  it  must  be  nearly  6  times  greater  than  the  force 
between  sodium  and  fluorine  ions.  Furthermore,  the  6 
fluorine  ions  would  surround  the  sulfur  ion  so  that  there 
would  be  little  stray  field  of  force.  Therefore,  we  should 
not  expect  sulfur  fluoride  to  be  salt-like  in  character  but 
to  consist  of  very  stable  molecules  having  weak  external 
fields  of  force  and,  therefore,  readily  existing  in  the  form 
of  a  gas.  As  a  matter  of  fact  this  extraordinary  sub- 
stance has  these  properties  developed  to  such  a  degree  that 
it  is  an  odorless  and  tasteless  gas  with  a  boiling  point  of 
— 62°.  Phosphorus  pentafluoride,  as  would  be  expected 
from  its  less  symmetrical  structure,  is  a  gas  having  greater 
cfhemical  activity. 

The  fluosilicate  ion  SiFg has  a  structure  exactly  like 

that  of  the  sulfur  fluoride  molecule  since  the  number  and 
arrangement  of  the  electrons  are  the  same.    This  is  clear 


30  CONTEMPORARY  SCIENCE 

if  we  consider  that  the  atomic  number  of  silicon  is  I4 
while  that  of  sulfur  is  16.  Thus  if  we  should  replace 
the  nucleus  of  the  sulfur  atom  in  a  molecule  of  sulfur 
fluoride  by  the  nucleus  of  a  silicon  atom,  without  dis- 
turbing any  of  the  surrounding  electrons,  we  would  have 
removed  two  positive  charges  and  would  obtain  a  nega- 
tive ion  with  two  negative  charges  of  the  formula  SiF^ . 

In  the  presence  of  potassium  ions  we  would  then  have 
the  familiar  salt  potassium  fluosilicate.  The  theory  is 
thus  capable  of  explaining  typical  complex  salts.  In  fact, 
it  is  applicable  to  the  whole  field  of  inorganic  compounds 
covered  by  the  work  of  Werner,  and  helps  to  simplify 
the  theory  of  such  compounds.  There  is  no  time,  how- 
ever, to  go  into  this  subject. 

The  simple  theory  of  atomic  structure  which  we  have 
discussed  thus  far  explains  perfectly  what  has  usually 
been  called  "the  maximum  positive  and  negative  valance." 
The  maximum  positive  valence  represents  the  number  of 
electrons  which  the  atom  possesses  in  excess  of  the  num- 
ber needed  to  form  one  of  the  particularly  stable  configu- 
rations of  electrons.  On  the  other  hand,  the  maximum 
negative  valence  is  the  number  of  electrons  which  the 
atom  must  take  up  in  order  to  reach  one  of  these  stable 
configurations. 

For  example,  magnesium  has  a  positive  valence  of  two, 
since  its  atomic  number  is  12  while  that  of  neon  is  10. 
Sulfur  has  a  positive  valence  of  6  since  it  has  6  electrons 
more  than  neon ;  but  it  has  a  negative  valence  of  two  be- 
cause it  must  take  up  two  more  electrons  before  it  can 
assume  a  form  like  that  of  the  argon  atom. 

It  is  clear,  however,  that  this  theory  of  valence  is  not 
yet  complete.^  It  is  not  applicable  to  those  cases  where 
we  have  usually  taken  valences  of  4  for  sulfur,  or  3  and 

^The  theories  of  Kossel,  Lacomble,  Teudt,  etc.,  which  have 
recently  been  proposed  in  Germany,  have  not  advanced  beyond 
this  point  and  are  therefore  very  unsatisfactory  as  a  general 
theory  of  valence. 


THE  STRUCTURE  OF  ATOMS  31 

5  for  chlorine,  etc.  But  more  especially  it  does  not  ex- 
plain the  structure  of  organic  compounds  and  such  sub- 
stances as  H2,  CI2,  O2,  N2H4,  PCI3,  etc. 

J.  J.  Thomson,  Stark,  Bohr,  and  others  had  suggested 
that  pairs  of  electrons  held  in  common  by  two  adjacerk 
atoms  may  function  in  some  cases  as  chemical  bonds  ht^ 
tween  the  atoms,  but  this  idea  had  not  been  combined  with 
the  conception  of  the  stable  groups  of  electrons  or  octets. 
G.  N.  Lewis,  in  an  important  paper  in  1916,  advanced  the 
idea  that  the  stable  configurations  of  electrons  in  atom 
could  share  pairs  of  electrons  with  each  other  and  he 
identified  these  pairs  of  electrons  with  the  chemical  bond 
of  organic  chemistry.  This  work  of  Lewis  has  been  the 
basis  and  the  inspiration  of  my  work  on  valence  and 
atomic  structure. 

As  a  result  of  the  sharing  of  electrons  between  octets, 
the  number  of  octets  that  can  be  formed  from  a  given 
number  of  electrons  is  increased.  For  example,  two 
fluorine  atoms,  each  having  seven  electrons  in  its  outside 
shell,  would  not  be  able  to  form  octets  at  all  except  by 
sharing  electrons.  By  sharing  a  single  pair  of  electrons, 
however,  two  octets  can  be  formed  since  two  octets  hold- 
ing a  pair  in  common  require  only  14  electrons.  This  is 
clear  if  we  consider  two  cubes  with  electrons  at  each  of 
the  eight  corners.  When  the  cubes  are  placed  so  that  an 
edge  of  one  is  in  contact  with  an  edge  of  the  other  a  sin- 
gle pair  of  electrons  at  the  ends  of  the  common  edge  will 
take  the  place  of  four  electrons  in  the  original  cubes. 
For  each  pair  of  electrons  held  in  common  between  two 
octets  there  is  a  decrease  of  two  in  the  total  number  of 
electrons  needed  to  form  the  octets. 

Let  e  represent  the  number  of  electrons  in  the  outside 
shell  of  the  atoms  that  combine  to  form  a  molecule.  Let 
n  be  the  number  of  octets  that  are  formed  from  these  e 
electrons,  and  let  p  be  the  number  of  pairs  of  electrons 
which  the  octets  share  with  one  another.  Since  every 
pair  of  electrons  thus  shared  reduces  by  two  the  number 


32  CONTEMPORARY  SCIENCE 

of  electrons  required  to  form  the  molecule  it  follows  that 
^  —  8m  —  2p  or 

p  =  ^(8n  — 0. 

This  simple  equation  tells  us  in  each  case  how  many 
pairs  of  electrons  or  chemical  bonds  must  exist  in  any- 
given  molecule  between  the  octets  formed.  Hydrogen 
nuclei,  however,  may  attach  themselves  to  pairs  of  elec- 
trons in  the  octets  which  are  not  already  shared.  For 
example,  in  the  formation  of  hydrogen  fluoride  from  a 
hydrogen  atom  and  a  flourine  atom  there  are  8  electrons 
in  the  shells  (^  =  B) .  We  place  n  —  i  in  the  above  equa- 
tion and  find  p  =  o.  In  other  words,  the  fluorine  atoms 
do  not  share  electrons  with  each  other.  The  hydrogen 
nucleus  having  given  up  its  electron  to  the  flourine  atom 
attaches  itself  to  one  of  the  pairs  of  electrons  of  the 
fluorine  octet,  and  thus  forms  a  molecule  having  a  rela- 
tively weak  external  field  of  force.  As  a  result,  hydrogen 
fluoride  is  a  liquid  of  low  boiling  point  instead  of  being 
salt-like  in  character. 

The  equation  given  above  is  applicable  to  all  types  of 
compounds.  For  example,  if  we  apply  it  to  substances 
such  as  sodium  fluoride,  sulfur  fluoride,  or  potassium 
fluosihcate,  which  were  previously  considered,  we  find  in 
each  case  p  =  o.  In  other  words,  there  are  no  pairs  of 
electrons  holding  the  atoms  of  these  compounds  together. 
On  the  other  hand  if  we  consider  the  compound  N2H4, 
we  find  p  —  I-  Since  there  are  only  two  octets  the  pair 
of  electrons  must  be  between  the  two  nitrogen  atoms 
while  the  hydrogen  nuclei  attach  themselves  to  pairs  of 
electrons  of  the  nitrogen  octets.  It  can  be  readily  shown 
that  this  simple  theory  is  in  fact  identical  with  the  ac- 
cepted valence  theory  of  organic  chemistry  and  leads  to 
the  same  structural  formulas  as  the  ordinary  theory  in 
all  those  cases  where  we  can  take  the  valance  of  nitrogen 
to  be  3,  oxygen  and  sulfur  2,  chlorine  and  hydrogen  one. 
In  other  cases  such  as  those  where  quinquivalent  nitrogen 
has  been  assumed,  the  new  theory  gives  results  different 


THE  STRUCTURE  OF  ATOMS  33 

from  the  old  but  in  each  case  in  better  agreement  with  the 
facts. 

The  theory  indicates  a  series  of  new  relationships  be- 
tween certain  types  of  substances  which  I  have  termed 
isosteric  substances.  For  example,  it  indicates  that  the 
molecules  of  carbon  dioxide  and  nitrous  oxide  should 
have  nearly  identical  structures  and  this  is  borne  out  by 
the  extraordinary  similarity  in  the  physical  properties 
of  these  gases.  Nitrogen  and  carbon  monoxide  constitute 
another  pair  of  gases  which  are  similarly  related.  The 
same  theory  also  points  out  a  number  of  previously  un- 
suspected cases  of  similarity  of  crystalline  form  (iso- 
morphism). 

It  is  clear  that  in  the  past  the  term  valence  has  been 
used  to  cover  what  we  may  now  recognize  as  three  differ- 
ent types  of  valence,  as  follows : 

I — Positive  valence:  the  number  of  electrons  an  atom 
can  give  up, 

2 — Negative  valence :  the  number  of  electrons  an  atom 
can  take  up, 

3 — Covalence :  the  number  of  pairs  of  electrons  which 
an  atom  can  share  with  its  neighbors. 

It  is  recommended  that  only  for  valences  of  the  coval- 
ence type  should  definite  bonds  be  indicated  in  chemical 
formulas.  One  of  the  particular  advantages  of  the  pres- 
ent theory  is  that  it  becomes  easy  to  distinguish  between 
covalence  and  the  other  types  and  thus  to  predict  with 
certainty  in  what  way  electrolytic  dissociation  will  occur 
if  at  all. 

REFERENCES 

K  Kossel,  Ann.  Physik,  49   (1916),  229. 

G.  N.  Lewis,  /.  Am.  Chem.  Soc,  38  (1916),  762. 

Langmuir,  /.  Frank.  Inst.,  187  (1919),  359;  /.  Am.  Chem.  Soc, 
41  (1919),  868,  1543;  42  (1920),  274;  Proc.  Nat.  Acad.  Set.,  5 
(1919),  252. 


ENGINEERING  BEFORE  AND  AFTER 
THE    WAR 

(Address  of  the  president  of  the  British  Asso- 
ciation for  the  Advancement  of  Science,  Bourne- 
mouth, 1919.) 

BY 

Sir  Charles  Parsons 
Developments  Prior  to  the  War 

James  Watt. — No  excuse  is  necessary  for  entering- 
upon  this  theme,  because  this  year  (1919)  marks  the 
hundredth  anniversary  of  the  death  of  James  Watt,  and 
in  reviewing  the  past,  it  appears  that  England  has  gained 
her  present  proud  position  by  her  early  enterprise  and 
by  the  success  of  the  Watt  steam  engine,  which  enabled 
her  to  become  the  first  country  to  develop  her  resources 
in  coal,  and  led  to  the  establishment  of  her  great  manu- 
factures and  her  immense  mercantile  marine. 

The  laws  of  steam  which  James  Watt  discovered  are 
simply  these :  That  the  latent  heat  is  nearly  constant  for 
different  pressures  within  the  ranges  used  in  steam  en- 
gines, and  that,  consequently,  the  greater  the  steam  pres- 
sure and  the  greater  the  range  of  expansion  the  greater 

34 


ENGINEERING  BEFORE  AND  AFTER  WAR    35 

will  be  the  work  obtained  from  a  given  amount  of  steam. 
Secondly,  as  may  now  seem  to  us  obvious,  that  steam 
from  its  expansive  force  will  rush  into  a  vacuum.  Hav- 
ing regard  to  the  state  of  knowledge  at  the  time,  his  con- 
clusions appear  to  have  been  the  result  of  close  and  pa- 
tient reasoning  by  a  mind  endowed  with  extraordinary 
powers  of  insight  into  physical  questions,  and  with  the 
faculty  of  drawing  sound  practical  conclusions  from 
numerous  experiments  devised  to  throw  light  on  the  sub- 
ject under  investigation.  His  resource,  courage  and  de- 
votion were  extraordinary. 

In  commencing  his  investigations  on  the  steam  engine 
he  soon  discovered  that  there  was  a  tremendous  loss  in 
the  Newcomen  engine,  which  he  thought  might  be  reme- 
died. This  was  the  loss  caused  by  condensation  of  the 
steam  on  the  cold  metal  walls  of  the  cylinder.  He  first 
commenced  by  lining  the  walls  with  wood,  a  material  of 
low  thermal  conductivity.  Though  this  improved  mat- 
ters, he  was  not  satisfied ;  his  intuition  probably  told 
him  that  there  should  be  some  better  solution  of  the  prob- 
lem, and  doubtless  he  made  many  experiments  before  he 
realised  that  the  true  solution  lay  in  a  condenser  separate 
from  the  cylinder  of  the  engine.  It  is  easy  after  discovery 
to  say,  "How  obvious  and  how  simple,"  but  many  of  us 
here  know  how  difficult  is  any  step  of  advance  when 
shrouded  by  unknown  surroundings,  and  we  can  well 
appreciate  the  courage  and  the  amount  of  investigation 
necessary  before  James  Watt  thought  himself  justified  in 
trying  the  separate  condenser.  But  to  us  now,  and  to  the 
youngest  student  who  knows  the  laws  of  steam  as  for- 
mulated by  Carnot,  Joule,  and  Kelvin,  the  separate  con- 
denser is  the  obvious  means  of  constructing  an  economi- 
cal condensing  engine. 

Watt's  experiments  led  him  to  a  clear  view  of  the  great 
importance  of  securing  as  much  expansion  as  possible  in 
his  engines.  The  materials  and  appliances  for  boiler  and 
machine  construction  were  at  that  time  so  undeveloped 


26  CONTEMPORARY  SCIENCE 

that  steam  pressures  were  practically  limited  to  a  few 
pounds  above  atmospheric  pressure.  The  cylinders  and 
pistons  of  his  engines  were  not  constructed  with  the  fa- 
cility and  accuracy  to  which  we  are  now  accustomed,  and 
chiefly  for  these  reasons  expansion  ratios  of  from  two 
to  threefold  were  the  usual  practice.  Watt  had  given  to 
the  world  an  engine  which  consumed  from  five  to  seven 
pounds  of  coal  per  horse-power  hour,  or  one-quarter  of 
the  fuel  previously  used  by  any  engine.  With  this  con- 
sumption of  fuel  its  field  under  the  conditions  prevailing 
at  the  time  was  practically  unlimited.  What  need  was 
there,  therefore,  for  commercial  reasons,  to  endeavor 
still  further  to  improve  the  engine  at  the  risk  of  encounter- 
ing fresh  difficulties  and  greater  commercial  embarrass- 
ments? The  course  was  rather  for  him  and  his  partners 
to  devote  all  their  energy  to  extend  the  adoption  of  the 
engine  as  it  stood,  and  this  they  did,  and  to  the  Watt 
engine,  consuming  from  five  to  seven  pounds  of  coal  per 
horse-power,  mankind  owes  the  greatest  permanent  ad- 
vances in  material  welfare  recorded  in  history. 

With  secondary  modifications,  it  was  the  prime  mover 
in  most  general  use  for  eighty  years — i.e.,  till  the  middle 
of  last  century.  It  remained  for  others  to  carry  the  ex- 
pansion of  steam  still  further  in  the  compound,  triple, 
and,  lastly,  in  the  quadruple  expansion  engine,  which  is 
the  most  economical  reciprocating  engine  of  to-day. 

Watt  had  considered  the  practicability  of  the  turbine. 
He  writes  to  his  partner,  Boulton,  in  1784:  "The  whole 
success  of  the  machine  depends  on  the  possibility  of 
prodigious  velocities.  In  s^hort,  without  God  makes  it 
possible  for  things  to  move  them  one  thousand  feet  per 
second,  it  cannot  do  us  much  harm."  The  advance  in 
tools  of  precision,  and  a  clearer  knowledge  of  the  dynam- 
ics of  rotating  bodies,  have  now  made  the  speeds  men- 
tioned by  Watt  feasible,  and  indeed  common,  everyday 
practice. 

Turbines. — The  turbine  of  to-day  carries  the  expansion 


ENGINEERING  BEFORE  AND  AFTER  WAR  37 

of  steam  much  further  than  has  been  found  possible  in 
any  reciprocating  engine,  and  owing  to  this  property  it 
has  surpassed  it  in  economy  of  coal,  and  it  realises  to  the 
fullest  extent  Watt's  ideal  of  the  expansion  of  steam  from 
the  boiler  to  the  lowest  vapor  pressure  obtainable  in 
the  condenser. 

Among  the  minor  improvements  which  in  recent  years 
have  conduced  to  a  higher  efficiency  in  turbines  are  the 
more  accurate  curv^ature  of  the  blades  to  avoid  eddy  losses 
in  the  steam,  the  raising  of  the  peripheral  velocities  of 
the  blades  to  nearly  the  velocity  of  the  steam  impinging 
upon  them,  and  details  of  construction  to  reduce  leakages 
to  a  minimum.  In  turbines  of  20,000  to  30,000  horse- 
power 82  per  cent,  of  the  available  energy  in  the  steam 
is  now  obtainable  as  brake  horse-power ;  and  with  a  boiler 
efficiency  of  85  per  cent,  the  thermo-dynamic  efficiency 
from  the  fuel  to  the  electrical  output  of  the  alternator 
has  reached  23  per  cent.,  and  shortly  may  reach  28  per 
cent.,  a  result  rivalling  the  efficiency  of  internal  combus- 
tion engines  worked  by  producer  gas. 

During  the  twenty  years  immediately  preceding  the 
war  turbo  generators  had  increased  in  size  from  500  kilo^ 
watts  to  25,000  kilowatts,  and  the  consumption  of  steam 
had  fallen  from  17  lb.  per  kw.  hour  to  10.3  lb.  per  kw. 
hour.  Turbines  have  become  the  recognised  means  of 
generating  electricity  from  steam  on  a  large  scale,  although 
they  have  not  superseded  the  Watt  engine  for  pumping 
mines  or  the  drawing  of  coal,  except  as  a  means  for 
generating  electricity  for  these  purposes.  In  the  same 
period  the  engine  power  in  the  mercantile  marine  had 
risen  from  3,900  of  the  King  Edward  to  75,000  of  the 
Mauretania, 

As  regards  the  Royal  Navy,  the  engine  power  of  battle- 
ships, prior  to  the  war,  had  increased  from  12,000  i.h.p. 
to  30,000  s.h.p.,  while  the  speed  advanced  from  17  knots 
to  23  knots,  and  during  the  war,  in  ships  of  the  Queen 
Elizabeth  class,  the  power   amounted   to   75,000  s.h.p.. 


38  CONTEMPORARY  SCIENCE 

with  a  speed  of  25  knots.  In  cruisers  similar  advances 
were  made.  The  i.h.p.  of  the  Powerful  was  25,000,  while 
the  s.h.p.  of  the  Queen  Mary  was  78,000,  with  a  speed 
of  28  knots.  During  the  war  the  power  obtained  with 
geared  turbines  in  the  Courageous  class  was  100,000  s.h.p. 
with  a  speed  of  32  knots,  the  maximum  power  trans- 
mitted through  one  gear  wheel  being  25,000  h.p.,  and 
through  one  pinion  15,500  h.p.,  while  in  destroyers,  speeds 
tip  to  39  knots  have  been  obtained.  The  aggregate  horse- 
power of  war  and  mercantile  turbined  vessels  throughout 
the  world  is  now  about  35  millions. 

These  advances  in  power  and  speed  'have  been  made 
possible  mainly  by  the  successive  increase  in  economy 
and  diminution  of  weight  derived  from  the  replacement 
of  reciprocating  engines  by  turbines  direct  coupled  to  the 
propellers,  and,  later,  by  the  introduction  of  reduction 
gearing  between  the  turbines  and  the  propellers ;  also  by 
the  adoption  of  water-tube  boilers  and  oil  fuel.  With 
these  advances  the  names  of  Lord  Fisher,  Sir  William 
White,  and  Sir  Henry  Oram  will  always  be  associated. 

The  British  Navy  has  led  the  world  for  a  century  and 
more.  Lord  Fisher  has  recently  said  that  many  of  the 
ships  are  already  obsolete  and  must  soon  be  replaced  if 
supremacy  is  to  be  maintained ;  and  there  can  be  no  ques- 
tion that  to  guide  the  advance  and  development  on  the 
best  lines,  continuous  scientific  experiment,  though  costly 
at  the  time,  will  prove  the  cheapest  in  the  long  run. 

The  Work  of  Sir  Wm.  White, — ^With  the  great  work 
of  the  Royal  Navy  fresh  in  our  minds,  we  cannot  but 
recall  the  prominent  part  taken  by  the  late  Sir  William 
White  in  its  construction.  His  sudden  death,  when  Presi- 
dent-elect for  191 3,  lost  to  the  nation  and  to  the  Associa- 
tion the  services  of  a  great  naval  architect  who  possessed 
remarkable  powers  of  prevision  and  dialectic.  He  was 
Chief  Constructor  to  the  Admiralty  from  1885  to  1901, 
and  largely  to  him  was  due  the  efficiency  of  our  vessels  in 
the  Great  War. 


ENGINEERING  BEFORE  AND  AFTER  WAR    39 

^  White  often  referred  to  the  work  of  Brunei  as  the  de- 
signer of  the  Great  Eastern,  and  spoke  of  him  as  the 
originator  of  the  cellular  construction  of  the  bottoms  of 
ships,  since  universally  adopted,  as  a  means  of  strengthen- 
ing the  hull  and  for  obtaining  additional  safety  in  case 
of  damage.  Scott  Russell  was  the  builder  of  this  great 
pioneer  vessel,  the  forerunner  of  the  Atlantic  liners,  and 
the  British  Association  may  rightly  feel  satisfaction  in 
having  aided  him  when  a  young  man  by  pecuniary  grants 
to  develop  his  researches  into  the  design  and  construction 
of  ships  and  the  wave-line  form  of  hull  which  he  origi- 
nated, a  form  of  special  importance  in  paddle-wheel  ves- 
sels. 

So  much  discussion  has  taken  place  in  the  last  four 
years  as  to  the  best  construction  of  ship  to  resist  torpedo 
attacks  that  it  is  interesting  to  recall  briefly  at  the  present 
time  what  was  said  by  White  in  his  Cantor  Lectures  to 
the  Royal  Society  of  Arts  in  1906:  "Great  attention  has 
been  bestowed  upon  means  of  defence  against  underwater 
torpedo  attacks.  From  the  first  introduction  of  torpedoes 
it  was  recognised  that  extreme  watertight  subdivision  in 
the  interior  of  warships  would  be  the  most  important 
means  of  defence.  Experiments  have  been  made  with 
triple  watertight  skins  forming  double  cellular  sides,  the 
compartments  nearest  the  outer  bottom  being  filled,  in 
some  cases,  with  water,  coal,  cellulose,  or  other  materials. 
Armor  plating  has  been  used  both  on  the  outer  bottom 
and  on  inner  skins.'*  He  also  alludes  to  several  Russian 
ships  which  were  torpedoed  by  the  Japanese,  and  he  con- 
cludes by  saying :  "Up  to  date  the  balance  of  opinion  has 
favored  minute  watertight  subdivisions  and  comparatively 
thin  watertight  compartments,  rather  than  the  use  of  in- 
ternal armor,  whose  use,  of  course,  involves  large  ex- 
penditure of  weight  and  cost." 

The  present  war  has  most  amply  confirmed  his  views 
and  conclusions,  then  so  lucidly  and  concisely  expressed. 

While  on  the  subject  of  steamships,  it  may  perhaps  be 


40  CONTEMPORARY  SCIENCE 

opportune  to  say  one  word  as  to  their  further  develop- 
ment. The  size  of  ships  has  been  steadily  increasing  up 
to  the  time  of  the  war,  resulting  in  a  reduction  of  power 
required  to  propel  them  per  ton  of  displacement.  On  the 
other  hand,  thanks  to  their  greater  size  and  more  eco- 
nomical machinery,  speeds  have  been  increased  when  the 
traffic  has  justified  the  greater  cost.  The  limiting  factor 
to  further  increase  in  size  is  the  depth  of  water  in  the 
harbors.  With  this  restriction  removed  there  is  no  ob- 
stacle to  building  ships  up  to  i,ooo  feet  in  length  or  more, 
provided  the  volume  and  character  of  the  traffic  are 
such  as  to  justify  the  capital  outlay. 

Tungsten  Steel, — Among  other  important  pre-war  de- 
velopments that  have  had  a  direct  bearing  upon  the  war, 
mention  should  be  made  of  the  discovery  and  extensive 
use  of  alloys  of  steel.  The  wonderful  properties  con- 
ferred upon  steel  by  the  addition  of  tungsten  were  dis- 
covered by  Muschet  ^  in  1868,  and  later  this  alloy  was  in- 
vestigated and  improved  by  Maunsel  White  and  Taylor, 
of  Philadelphia.  The  latter  showed  that  the  addition  of 
tungsten  to  steel  has  the  following  effect :  That  after  the 
steel  has  been  quenched  at  a  very  high  temperature  near 
its  melting  point  it  can  be  raised  to  a  much  higher  tem- 
perature than  is  possible  with  ordinary  carbon  tool  steel, 
without  losing  its  hardness  and  power  of  cutting  metal. 
In  other  words,  it  holds  the  carbon  more  tenaciously  in 
the  hardened  state,  and  hence  tungsten  steel  tools,  even 
when  red  hot,  can  cut  ordinary  mild  steel.  It  has  revo- 
lutionised the  design  of  machine  tools  and  has  increased 
the  output  on  heavy  munition  work  by  100  per  cent.,  and 
in  ordinary  engineering  by  50  per  cent. 

The  alloys  of  steel  and  manganese  with  which  the 
name  of  Sir  Robert  Hadfield  is  associated  have  proved 
of  utility  in  immensely  increasing  the  durability  of  rail- 
way and  tramway  points  and  crossings,  and  for  the  hard 

iWho  has  not  been  sufficiently  credited  with  his  share  m 
making  the  Bessemer  process  a  practical  success. 


ENGINEERING  BEFORE  AND  AFTER  WAR  41 

teeth  of  machinery  for  the  crushing  of  stone  and  other 
materials,  and,  in  fact,  for  any  purposes  where  great 
hardness  and  strength  are  essential. 

Investigation  of  Gaseous  Explosions. — Brief  reference 
must  also  be  made — and  it  will  be  gratifying  to  do  so — 
to  the  important  work  of  one  of  the  Committees  of  the 
British  Association  appointed  in  1908,  under  the  chair- 
manship of  the  late  Sir  William  Preece,  for  the  investi- 
gation of  gaseous  explosions,  with  special  reference  to 
temperature.  The  investigations  of  the  Committee  are 
contained  in  seven  yearly  reports  up  to  1914.  Of  the 
very  important  work  of  the  Committee  I  wish  to  refer  to 
one  investigation  in  particular,  which  has  proved  to  be  a 
guiding  star  to  the  designers  and  manufacturers  of  in- 
ternal combustion  engines  in  this  country.  The  members 
of  the  Committee  more  directly  associated  with  this  par- 
ticular investigation  were  Sir  Dugald  Clerk,  Professor 
Callendar,  and  the  late  Professor  Bertram  Hopkinson. 

The  investigation  showed  that  the  intensity  of  the  heat 
radiated  by  the  incandescent  gases  to  the  walls  of  the  cyl- 
inder of  a  gas  engine  increases  with  the  size  of  the  cyl- 
inder, the  actual  rate  of  this  increase  being  approximately 
proportional  to  the  square  root  of  the  depth  of  the  radiat- 
ing incandescent  gas ;  the  intensity  was  also  shown  to  in- 
crease rapidly  with  the  richness  of  the  gas.  It  suffices 
now  to  say  that  the  heat  in  a  large  cylinder  witli  a  rich 
explosive  mixture  is  so  intense  that  the  metal  eventually 
cracks.  The  investigation  shows  why  this  occurs,  and  by 
doing  so  has  saved  enormous  sums  to  the  makers  of  gas 
and  oil  engines  in  this  country,  and  has  led  them  to  avoid 
the  large  cylinder,  so  common  in  Germany  before  the  war, 
in  favor  of  a  multiplicity  of  smaller  cylinders. 

SCIENCE   AND  THE   WAR 

Four  years  is  too  short  a  time  for  much  scientific  in- 
vention to  blossom  to  useful  maturity,  even  under  the 


42  CONTEMPORARY  SCIENCE 

forced  exigencies  of  war  and  Government  control.  It 
must  be  remembered  that  in  the  past  the  great  majority 
of  new  discoveries  and  inventions  of  merit  have  taken 
many  years — sometimes  generations — to  bring  them  into 
general  use.  It  must  also  be  mentioned  that  in  some 
instances  discoveries  and  inventions  are  attributable  to 
the  general  advance  in  Science  and  the  Arts  which  has 
brought  within  the  region  of  practical  politics  an  attack 
on  some  particular  problem.  So  the  work  of  the  scientists 
during  the  war  has  perforce  been  directed  more  to  the 
application  of  known  principles,  trade  knowledge,  and 
properties  of  matter  to  the  waging  of  war,  than  to  the 
making  of  new  and  laborious  discoveries ;  though,  in  ef- 
fecting such  applications,  inventions  of  a  high  order  have 
been  achieved,  some  of  which  promise  to  be  of  great  use- 
fulness in  time  of  peace. 

The  advance  of  Science  and  the  Arts  in  the  last  cen- 
tury had,  however,  wrought  a  great  change  in  the  imple- 
ments of  war.  The  steam  engine,  the  internal  combustion 
engine,  electricity,  and  the  advances  in  metallurgy  and 
chemistry  had  led  to  the  building  up  of  immense  industries 
which,  when  diverted  from  their  normal  uses,  have  pro- 
duced unprecedented  quantities  of  war  material  for  the 
enormous  armies,  and  also  for  the  greatest  Navy  which 
the  world  has  ever  seen. 

The  destructive  energy  in  the  field  and  afloat  has  mul- 
tiplied many  hundredfold  since  the  time  of  the  Napoleonic 
wars;  both  before  and  during  the  war  the  size  of  guns 
and  the  efficiency  of  explosives  and  shell  increased  im- 
mensely, and  many  new  implements  of  destruction  were 
added.  Modern  Science  and  Engineering  enabled  armies 
unprecedented  in  size,  efficiency  and  equipment  to  be 
drawn  from  all  parts  of  the  world  and  to  be  concentrated 
rapidly  in  the  fighting  line. 

To  build  up  the  stupendous  fighting  organization,  ships 
have  been  taken  from  their  normal  trade  routes,  locomo- 
tives and  material  from  the  home  railways,  the  normal 


ENGINEERING  BEFORE  AND  AFTER  WAR  43 

manufactures  of  the  country  have  been  largely  diverted 
to  munitions  of  war;  the  home  railways,  tramways,  roads, 
buildings  and  constructions,  and  material  of  all  kinds  have 
been  allowed  to  depreciate.  The  amount  of  depreciation 
in  roads  and  railways  alone  has  been  estimated  at  400 
millions  per  annum  at  present  prices.  Upon  the  com- 
munity at  home  a  very  great  and  abnormal  strain  has  been 
thrown,  notwithstanding  the  increased  output  per  head  of 
the  workers  derived  from  modern  methods  and  improved 
machinery.  In  short,  we  have  seen  for  the  first  time  in 
history  nearly  the  whole  populations  of  the  principal  con- 
tending nations  enlisted  in  intense  personal  and  collective 
effort  in  the  contest,  resulting  in  unprecedented  loss  of 
life  and  destruction  of  capital. 

A  few  figures  will  assist  us  to  realize  the  great  differ- 
ence between  this  war  and  all  preceding  wars.  At  Water- 
loo, in  181 5,  9,044  artillery  rounds  were  fired,  having  a 
total  weight  of  37.3  tons,  while  on  one  day  during  the  last 
offensive  in  France,  on  the  British  Front  alone,  943,837 
artillery  rounds  were  fired,  weighing  18,080  tons — over 
100  times  the  number  of  rounds,  and  485  times  the  weight 
of  projectiles.  Again,  in  the  whole  of  the  South  African 
War,  273,000  artillery  rounds  were  fired,  weighing  ap- 
proximately 2,800  tons;  while  during  the  whole  war  in 
France,  on  the  British  Front  alone,  over  170  million 
artillery  rounds  were  fired,  weighing  nearly  3^  million 
tons — 622  times  the  number  of  rounds,  and  about  1,25a 
times  the  weight  of  projectiles. 

However  great  these  figures  in  connection  with  modern 
land  artillery  may  be,  they  become  almost  insignificant 
when  compared  with  those  in  respect  of  a  modern  naval 
battle  squadron.  The  Queen  Elisabeth  when  firing  all 
her  guns  discharges  18  tons  of  metal  and  develops  1,870,- 
000  foot-tons  of  energy.  She  is  capable  of  repeating  this 
discharge  once  every  minute,  and  when  doing  so  develops 
by  her  guns  an  average  of  127,000  effective  horse-power^ 
or  more  than  one-and-a-half  times  the  power  of  her  pro- 


44  CONTEMPORARY  SCIENCE 

pelling  machinery;  and  this  energy  is  five  times  greater 
than  the  maximum  average  developed  on  the  Western 
Front  by  British  guns.  Furthermore,  if  all  her  guns  were 
fired  simultaneously,  they  would  for  the  instant  be  de- 
veloping energy  at  the  rate  of  13,132,000  horse-power. 
From  these  figures  we  can  form  some  conception  of  the 
vast  destructive  energy  developed  in  a  modern  naval 
battle. 

Engineering  and  the  War, 

Sound-ranging  and  Listening  Devices. — Probably  the 
most  interesting  development  during  the  war  has  been 
the  extensive  application  of  sound-listening  devices  for 
detecting  and  localizing  the  enemy.  The  Indian  hunter 
puts  his  ear  to  the  ground  to  listen  for  the  sound  of  the 
footsteps  of  his  enemy.  So  in  modern  warfare  science 
has  placed  in  the  hands  of  the  sailor  and  soldier  elaborate 
instruments  to  aid  the  ear  in  the  detection  of  noises 
transmitted  through  earth,  water,  air,  or  ether,  and  also 
in  some  cases  to  record  these  sounds  graphically  or  photo- 
graphically, so  that  their  character  and  the  time  of  their 
occurrence  may  be  tabulated. 

The  sound-ranging  apparatus  by  which  the  position  of 
an  enemy  gun  can  be  determined  from  electrically  re- 
corded times  at  which  the  sound  wave  from  the  gun 
passes  over  a  number  of  receiving  stations,  has  enabled 
our  artillery  to  concentrate  their  fire  on  the  enemy's  guns, 
and  often  to  destroy  them. 

The  French  began  experimenting  in  September,  1914, 
with  methods  of  locating  enemy  guns  by  sound.  The 
English  section  began  work  in  October,  191 5,  adopting 
the  French  methods  in  the  first  instance.  By  the  en^  of 
1916  the  whole  Front  was  covered,  and  sound-ranging 
began  to  play  an  important  part  in  the  location  of  enemy 
batteries.  During  191 7  locations  by  sound-ranging 
reached  about  30,000  for  the  whole  army,  this  number 


ENGINEERING  BEFORE  AND  AFTER  WAR  4$ 

being  greater  than  that  given  by  any  other  means  of 
location.  A  single  good  set  of  observations  could  be  re- 
lied upon  to  give  the  position  of  an  enemy  gun  to  about 
50  yards  at  7,000  yards  range.  It  could  also  be  carried 
on  during  considerable  artillery  activity. 

The  apparatus  for  localizing  noises  transmitted  through 
the  ground  has  been  much  used  for  the  detection  of  enemy 
mining  and  counter-mining  operations.  Acoustic  tubes^ 
microphones,  and  amplifying  valves  have  been  employed 
to  increase  the  volume  of  very  faint  noises. 

For  many  years  before  the  war  the  Bell  Submarine  Sig^ 
naling  Company,  of  which  Sir  William  White  was  one  of 
the  early  directors,  used  submerged  microphones  for  de- 
tecting sound  transmitted  through  the  water,  and  a  sub- 
merged bell  for  sending  signals  to  distances  up  to  one 
mile.  With  this  apparatus  passing  ships  could  be  heard 
at  a  distance  of  nearly  a  mile  when  the  sea  was  calm  and 
the  listening  vessel  stationary. 

Of  all  the  physical  disturbances  emitted  or  produced 
by  a  moving  submarine,  those  most  easily  detected,  and 
at  the  greatest  distance,  are  the  pressure  waves  set  up  in 
the  water  by  vibrations  produced  by  the  vessel  and  her 
machinery.  A  great  variety  of  instruments  have  been 
devised  during  the  war  for  detecting  these  noises,  depend- 
ing on  microphones  and  magnetophones  of  exceedingly 
high  sensitivity.  Among  them  may  be  particularly  men- 
tioned the  hydrophones  devised  by  Captain  Ryan  and 
Professor  Bragg,  being  adaptations  of  the  telephone  trans- 
mitter to  work  in  water,  instead  of  air.  These  instru- 
ments, when  mounted  so  as  to  rotate,  are  directional,  be- 
ing insensitive  to  sound  waves  whose  front  is  perpendicu- 
lar to  the  plane  of  the  diaphragm,  and  giving  the 
loudest  sound  when  the  diaphragm  is  parallel  to  the  wave 
front. 

Another  preferable  method  for  determining  direction 
is  to  use  two  hydrophones  coupled  to  two  receivers,  one 
held  to  each  ear.    This  is  called  the  biaural  method,  and 


46  CONTEMPORARY  SCIENCE 

enables  the  listener  to  recognize  the  direction  from  which 
the  sound  emanates. 

When  the  vessel  is  in  motion  or  the  sea  is  rough  the 
water  noises  from  the  dragging  of  the  instrument  through 
the  water  and  from  the  waves  striking  the  ship  drown 
the  noises  from  the  enemy  vessel,  and  under  such  condi- 
tions the  instruments  are  useless.  The  assistance  of  emi- 
nent biologists  was  of  invaluable  help  at  this  juncture. 
Experiments  were  made  with  sea-lions  by  Sir  Richard 
Paget,  who  found  that  they  have  directional  hearing 
under  water  up  to  speeds  of  six  knots.  Also  Professor 
Keith  explained  the  construction  of  the  hearing  organs 
of  the  whale,  the  ear  proper  being  a  capillary  tube,  too 
small  to  be  capable  of  performing  any  useful  function  in 
transmitting  sound  to  the  relatively  large  aural  organs, 
which  are  deep  set  in  the  head.  The  whale  therefore 
hears  by  means  of  the  sound  waves  transmitted  through 
the  substance  of  the  head.  It  was  further  seen  that  the 
organs  of  hearing  of  the  whale  to  some  degree  resembled 
the  hydrophone. 

The  course  now  became  clear.  Hollow  towing  bodies 
in  the  form  of  fish  or  porpoises  were  made  of  celluloid, 
varnished  canvas,  or  very  thin  metal,  and  the  hydrophone 
suitably  fixed  in  the  center  of  the  head.  The  body  is 
iilled  with  water,  and  the  cable  towing  the  fish  contains 
the  insulated  leads  to  the  observer  on  board  the  vessel. 
When  towed  at  some  distance  behind  the  chasing  ship 
disturbing  noises  are  small,  and  enemy  noises  can  be 
heard  up  to  speeds  of  14  knots,  and  at  considerable  dis- 
tances. Thermionic  amplifying  valves  have  been  exten- 
sively used,  and  have  added  much  to  the  sensitiveness  of 
the  hydrophone  in  its  many  forms. 

After  the  loss  of  the  Titanic  by  collision  with  an  iceberg, 
Lewis  Richardson  was  granted  two  patents  in  1912  for 
the  detection  of  above-water  objects  by  their  echo  in  the 
air,  and  underwater  objects  by  their  echo  transmitted 
through  the  water.    The  principles  governing  the  produc- 


ENGINEERING  BEFORE  AND  AFTER  WAR  47 

tion  and  the  concentration  of  beams  of  sound  are  de- 
scribed in  his  specifications,  and  he  recommends  fre- 
quencies ranging  from  4,786  to  100,000  complete  vibra- 
tions per  second,  and  also  suggests  that  the  rate  of 
approach  or  recession  from  the  object  may  be  determined 
from  the  difference  in  the  pitch  of  the  echo  from  the  pitch 
of  the  blast  sent  out.  Hiram  Maxim  also  suggested  simi- 
lar apparatus  a  little  later. 

The  echo  method  of  detection  was  not,  however,  prac- 
tically developed  until  French  and  English  scientists,  with 
whom  was  associated  Professor  Langevin,  of  the  College 
de  France,  realizing  its  importance  for  submarine  detec- 
tion, brought  the  apparatus  to  a  high  degree  of  perfection 
and  utility  shortly  before  the  Armistice.  Now,  with  beams 
of  high-frequency  sound  waves,  it  is  possible  to  sweep 
the  seas  for  the  detection  of  any  submerged  object,  such 
as  icebergs,  submarines,  surface  vessels,  and  rocks;  they 
may  also  be  used  to  make  soundings.  It  enables  a  chas- 
ing ship  to  pick  up  and  close  in  on  a  submarine  situated 
more  than  a  mile  away. 

The  successful  development  of  sound-ranging  apparatus 
on  land  led  to  the  suggestion  by  Professor  Bragg  that  a 
modified  form  could  be  used  to  locate  under-water  ex- 
plosions. It  has  been  found  that  the  shock  of  an  explosion 
can  be  detected  hundreds  of  miles  from  its  source  by 
means  of  a  submerged  hydrophone,  and  that  the  time  of 
the  arrival  of  the  sound  wave  can  be  recorded  with  great 
precision.  At  the  end  of  the  war  the  sound-ranging  sta- 
tions were  being  used  for  the  detection  of  positions  at 
sea,  required  for  strategical  purposes.  The  same  stations 
are  now  being  used  extensively  for  the  determination  of 
such  positions  at  sea  as  light-vessels,  buoys  which  indicate 
channels,  and  obstructions  such  as  sunken  ships.  By  this 
means  ships  steaming  in  fog  can  be  given  their  positions 
with  accuracy  for  ranges  up  to  500  miles. 

Among  the  many  other  important  technical  systems  and 
devices  brought  out  during  the  war  which  will  find  useful 


48  CONTEMPORARY  SCIENCE 

application  under  peace  conditions  as  aids  to  navig-ation 
I  may  mention  directional  wireless,  by  which  ships  and 
aircraft  can  be  given  their  positions  and  directed. 

Leader  gear,  first  used  by  the  Germans  to  direct  their 
ships  through  their  minefields,  and  subsequently  used  by 
the  Allies,  consists  of  an  insulated  cable  laid  on  the  bot- 
tom of  the  sea,  earthed  at  the  farther  end,  and  through 
which  an  alternating  current  is  passed.  By  means  of 
delicate  devices  installed  on  a  ship,  she  is  able  to  follow 
the  cable  at  any  speed  with  as  much  precision  as  a  rail- 
less  electric  'bus  can  follow  its  trolley  wire.  Cables  up 
to  50  miles  long  have  been  used,  and  this  device  prom- 
ises to  be  invaluable  to  ships  navigating  narrow  and  tor- 
tuous channels  and  entering  or  leaving  harbors  in  a 
fog. 

Aircraft. — It  may  be  justly  said  that  the  development  in 
aircraft  design  and  manufacture  is  one  of  the  astonishing 
engineering  feats  of  the  war.  In  August,  1914,  the  Brit- 
ish Air  Service  possessed  a  total  of  272  machines, 
whereas  in  October,  1918,  just  prior  to  the  Armistice,  the 
Royal  Air  Force  possessed  over  22,000  effective  machines. 
During  the  first  twelve  months  of  the  war  the  average 
monthly  delivery  of  aeroplanes  to  our  Flying  Service  was 
fifty,  while  during  the  last  twelve  months  of  the  war  the 
average  deliveries  were  2,700  per  month.  So  far  as  aero- 
engines are  concerned,  our  position  in  1914  was  by  no 
means  satisfactory.  We  depended  for  a  large  proportion 
of  our  supplies  on  other  countries.  In  the  Aerial  Derby 
of  1913,  of  the  eleven  machines  that  started,  not  one  had 
a  British  engine.  By  the  end  of  the  war,  however,  British 
^  aero-engines  had  gained  the  foremost  place  in  design  and 
manufacture,  and  Vv^ere  well  up  to  requirements  as  regards 
supply.  The  total  horse-power  produced  in  the  last  twelve 
months  of  the  war  approximated  to  eight  millions  of  brake 
horse-power,  a  figure  quite  comparable  with  the  total 
horse-power  of  the  marine  engine  output  of  the  country. 

In  view  of  the  recent  trans-Atlantic  flights,  I  feel  that 


ENGINEERING  BEFORE  AND  AFTER  WAR  49 

it  may  be  opportune  to  make  the  following  observations 
on  the  comparative  utility  of  aeroplanes  and  airships  for 
commercial  purposes.  In  the  case  of  the  aeroplane,  the 
weight  per  horse-power  increases  with  the  size,  other 
things  being  equal.  This  increase,  however,  is  met  to  some 
extent  by  a  multiplicity  of  engines,  though  in  the  fusilage 
the  increase  remains. 

On  the  other  hand,  with  the  airship  the  advantage  in- 
creases with  the  size,  as  in  all  ships.  The  tractive  effort 
per  ton  of  displacement  diminishes  in  inverse  proportion 
to  the  dimensions,  other  things,  including  the  speed,  being 
the  same.  Thus,  an  airship  of  750  feet  length  and  60 
tons  displacement  may  require  a  tractive  force  of  5  per 
cent.,  or  3  tons,  at  60  miles  per  hour;  while  one  of  1,500 
feet  in  length  and  8  X  60  =  480  tons  displacement  would 
only  require  2J/2  per  cent.  X  480  =12  tons  at  the  same 
speed,  and  would  carry  fuel  for  double  the  distance. 

With  the  same  proportion  of  weight  of  hull  to  displace- 
ment, the  larger  airship  would  stand  double  the  wind  pres- 
sure, and  would  weather  storms  of  greater  violence  and 
hailstones  of  greater  size.  It  would  be  more  durable,  the 
proportional  upkeep  would  be  less,  and  the  proportional 
loss  of  gas  considerably  less.  In  other  words,  it  v/ould 
lose  a  less  proportion  of  its  buoyancy  per  day.  It  is  a 
development  in  which  success  depends  upon  the  project 
being  well  thought  out  and  the  job  being  thoroughly  well 
done.  The  equipment  of  the  airsheds  with  numerous 
electric  haulage  winches,  and  all  other  appliances  to  make 
egress  and  ingress  to  the  sheds  safe  from  danger  and  ac-« 
cident,  must  be  ample  and  efficient. 

The  airship  appears  to  have  a  great  future  for  special 
commerce  where  time  is  a  dominant  factor  and  the  de- 
mand is  sufficient  to  justify  a  large  airship.  It  has  also 
a  great  field  in  the  opening  up  of  new  countries  where 
other  means  of  communication  are  difficult.  The  only 
limitation  to  size  will  be  the  cost  of  the  airship  and  its 
sheds,  just  as  in  steam  vessels  it  is  the  cost  of  the  vessels 


50  CONTEMPORARY  SCIENCE 

and  the  cost  of  deepening  the  harbors  that  limit  the  size 
of  Atlantic  liners. 

Such  developments  generally  take  place  slowly,  other- 
wise failures  occur — as  in  the  case  of  the  Great  Eastern 
— and  it  may  be  many  years  before  the  airship  is  increased 
from  the  present  maximum  of  750  feet  to  1,500  feet  with 
success,  but  it  will  assuredly  come.  If,  however,  the  de- 
velopment is  subsided  or  assisted  by  government  in- 
cidental failures  may  be  faced  with  equanimity  and  very 
rapid  development  accomplished.^  In  peace  time  the  sea- 
plane, aeroplane,  and  airship  will  most  certainly  have 
their  uses.  But,  except  for  special  services  of  high  utility, 
it  is  questionable  whether  they  will  play  more  than  a 
minor  part  as  compared  with  the  steamship,  railway,  and 
motor  transport. 

Electricity, — The  supply  and  use  of  electricity  has  de- 
veloped rapidly  in  recent  years.  For  lighting  it  is  the  rival 
of  gas,  though  each  has  its  advantages.  As  a  means  of 
transmitting  power  over  long  distances  it  has  no  rival, 
and  its  efficiency  is  so  high  that  when  generated  on  a 
large  scale  and  distributed  over  large  areas  it  is  a  cheap 
and  reliable  source  of  power  for  working  factories,  tram- 
ways, suburban  railways,  and  innumerable  other  pur- 
poses, including  metallurgical  and  chemical  processes.  It 
is  rapidly  superseding  locally  generated  steam-power,  and 
is  a  rival  to  the  small  and  moderate-sized  gas  and  oil 
engine.  It  has  made  practicable  the  use  of  water-power 
through  the  generation  of  electricity  in  bulk  at  the  natural 
falls,  from  which  the  power  is  transmitted  to  the  consum- 
ers, sometimes  at  great  distances. 

Fifteen  years  ago  electricity  was  generated  chiefly  by 
large  reciprocating  steam  engines,  direct  coupled  to  dyna- 
mos or  alternators,  but  of  late  years  steam  turbines  have 
in  most  instances  replaced  them,  and  are  now  exclusively 
used  in  large  generating  stations,  because  of  their  smaller 

^The  literature  on  this  subject  includes  an  article  which  ap- 
peared in  Engineering  on  January  3,  1919. 


ENGINEERING  BEFORE  AND  AFTER  WAR    51 

cost  and  greater  economy  in  fuel.  The  size  of  the  turbines 
may  vary  from  a  few  thousand  horse-power  up  to  about 
50,000  horse-power.  At  the  end  of  last  year  the  central 
electric  stations  in  the  United  Kingdom  contained  plant 
aggregating  2^  million  kilowatts,  79  per  cent,  of  which 
was  driven  by  steam  turbines. 

Much  discussion  has  taken  place  as  to  the  most  eco- 
nomical size  of  generating  stations,  their  number,  the  size 
of  the  generating  units,  and  the  size  of  the  area  to  be  sup- 
plied. On  the  one  hand,  a  comparatively  small  number 
of  very  large  or  super-stations,  instead  of  a  large  number 
of  moderate-sized  stations  dotted  over  the  area,  results 
in  a  small  decrease  in  the  cost  of  production  of  the  elec- 
tricity, because  in  the  super-stations  larger  and  slightly 
more  economical  engines  are  employed,  while  the  larger 
stations  permit  of  higher  organization  and  more  elaborate 
labor-saving  appliances.  Further,  if  in  the  future  the 
recovery  of  the  by-products  of  coal  should  become  a  prac- 
tical realization  as  part  of  the  process  in  the  manufacture 
of  the  electric  current,  the  larger  super-stations  present 
greater  facilities  than  the  smaller  stations.  On  the  other 
hand,  super-stations  involve  the  transmission  of  the  elec- 
tricity over  greater  distances,  and  consequently  greater 
capital  expenditure  and  cost  of  maintenance  of  mains  and 
transmission  apparatus,  and  greater  electrical  transmission 
losses,  while  the  larger  generating  unit  takes  longer  to 
overhaul  or  repair,  and  consequently  a  larger  percentage 
of  spare  plant  is  necessary. 

The  greatest  element  in  reducing  the  cost  of  electricity 
is  the  provision  of  a  good  load  factor ;  in  other  words,  the 
utilization  of  the  generating  plant  and  mains  to  the  great- 
est extent  during  the  twenty-four  hours  of  each  day 
throughout  the  year.  This  is  a  far  more  important  con- 
sideration than  the  size  of  the  station,  and  it  is  secured 
to  the  best  advantage  in  most  cases  by  a  widespread  net- 
work of  mains,  supplying  a  diversity  of  consumers  and 
uses,  each  requiring  current  at  different  times  of  the  day. 


52  CONTEMPORARY  SCIENCE 

The  total  load  of  each  station  bein^  thus  an  average  of 
the  individual  loads  of  a  number  of  consumers  is,  in  gen- 
eral, far  less  fluctuating  than  in  the  case  of  small  generat- 
ing and  distributing  systems,  which  supply  principally 
one  class  of  consumer,  a  state  of  affairs  that  exists  in 
London,  for  instance,  at  the  present  time.  It  is  true  that 
there  may  be  exceptional  cases,  such  as  at  Kilmarnock, 
where  a  good  load  factor  may  be  found  in  a  small  area, 
but  in  this  case  the  consumers  are  chiefly  mills,  which  re- 
quire current  for  many  hours  daily. 

There  is  no  golden  rule  to  secure  cheap  electricity.  The 
most  favorable  size,  locality,  and  number  of  generating 
stations  in  each  area  can  only  be  arrived  at  by  a  close 
study  of  the  local  conditions,  but  there  is  no  doubt  that, 
generally  speaking,  to  secure  cheap  electricity  a  wide- 
spread network  of  mains  is  in  most  cases  a  very  impor- 
tant, if  not  an  essential,  factor. 

The  electrification  of  tramways  and  suburban  railways 
has  been  an  undoubted  success  where  the  volume  of  traffic 
has  justified  a  frequent  service,  and  it  has  been  remark- 
able that  where  suburban  lines  have  been  worked  by 
frequent  and  fast  electrical  trains  there  has  resulted  a 
great  growth  of  passenger  traffic.  The  electrification  of 
rnain  line  railways  would  no  doubt  result  in  a  saving  of 
c-oal;  at  the  same  time,  the  economical  success  would 
largely  depend  on  the  broader  question  as  to  whether  the 
volume  of  the  traffic  would  suffice  to  pay  the  working 
expenses,  and  provide  a  satisfactory  return  on  the 
capital. 

Municipal  and  company  generating  stations  have  been 
nearly  doubled  in  capacity  during  the  war  to  meet  the 
demand  from  munition  works,  steel  works,  chemical 
works,  and  for  many  other  purposes.  The  provision  of 
this  increased  supply  was  an  enormous  help  in  the  pro- 
duction of  adequate  munitions.  At  the  commencement  of 
the  war  there  were  few  steel  electric  furnaces  in  the  coun- 
try;  at  the  end  of  last  year  117  were  at  work,  producing 


ENGINEERING  BEFORE  AND  AFTER  WAR    53 

20,000  tons  of  steel  per  month,  consisting  chiefly  of  high- 
grade  ferro  alloys  used  in  munitions. 

The   Future 

The  nations  who  have  exerted  the  most  influence  in  the 
war  have  been  those  who  have  developed  to  the  greatest 
extent  of  their  resources,  their  manufactures,  and  their 
commerce.  As  in  the  war,  so  in  civilization  of  mankind. 
But,  viewing  the  present  trend  of  developments  in  har- 
nessing water-power  and  using  up  the  fuel  resources  of 
the  world  for  the  use  and  convenience  of  man,  one  cannqt 
but  realize  that,  failing  new  and  unexpected  discoveries 
in  science,  such  as  the  harnessing  of  the  latent  molecular 
and  atomic  energy  in  matters,  as  foreshadowed  by  Qerk 
Maxwell,  Kelvin,  Rutherford,  and  others,  the  great  posi- 
tion of  England  cannot  be  maintained  for  an  indefinite 
period.  At  some  time  more  or  less  remote — long  before 
the  exhaustion  of  our  coal — ^the  population  will  gradually 
migrate  to  those  countries  where  the  natural  sources  of 
energy  are  the  most  abundant. 

Water-power  and  Coal. — The  amount  of  available 
water-power  in  the  British  Isles  is  very  small  as  compared 
with  the  total  in  other  countries.  According  to  the  latest 
estimates,  the  total  in  the  British  Isles  is  under  i  J^  million 
horse-power,  whereas  Canada  alone  possesses  over  20  mil- 
lions, of  which  over  2  millions  have  already  been  har- 
nessed. In  the  rest  of  the  British  Empire  there  are  up- 
wards of  30  millions  and  in  the  remainder  of  the  world  at 
least  150  millions,  so  that  England  herself  possesses  less 
than  I  per  cent,  of  the  water-power  of  the  world. 
Further,  it  has  been  estimated  that  she  possesses  only  2j4 
per  cent,  of  the  whole  coal  of  the  world.  To  this  question 
I  would  wish  to  direct  our  attention  for  a  few  minutes. 

I  have  said  that  England  owes  her  modern  greatness  to 
the  early  development  of  her  coal.  Upon  it  she  must  con- 
tinue to  depend  almost  exclusively  for  her  heat  and  source 


54  CONTEMPORARY  SCIENCE 

of  power,  including  that  required  for  propelling  her  vast 
mercantile  marine.  Nevertheless,  she  is  using  up  her  re- 
sources in  coal  much  more  rapidly  than  most  other  coun- 
tries are  consuming  theirs,  and  long  before  any  near  ap- 
proach to  exhaustion  is  reached  her  richer  seams  will 
have  become  impoverished,  and  the  cost  of  mining  so 
much  increased  that,  given  cheap  transport,  it  might  pay 
her  better  to  import  coal  from  richer  fields  of  almost 
limitless  extent  belonging  to  foreign  countries,  and  work- 
able at  a  much  lower  cost  than  her  own. 

Let  us  endeavor  to  arrive  at  some  approximate  estimate 
of  the  economic  value  of  the  principal  sources  of  power. 
The  present  average  value  of  the  royalties  on  coal  in 
England  is  about  6d.  per  ton,  but  to  this  must  be  added 
the  profit  derived  from  mining  operations  after  paying 
royalties  and  providing  for  interest  on  the  capital  ex- 
pended and  for  its  redemption  as  wasting  capital.  After 
consultation  with  several  leading  experts  in  these  matters, 
I  have  come  to  the  conclusion  that  about  i^.  per  ton  rep- 
resents the  pre-war  market  value  of  coal  in  the  seams  in 
England. 

It  must,  however,  be  remembered  that,  in  addition,  coal 
has  a  considerable  value  as  a  national  asset,  for  on  it  de- 
pends the  prosperity  of  the  great  industrial  interests  of 
the  country,  which  contribute  a  large  portion  of  the  wealth 
and  revenue.  From  this  point  of  view  the  present  value 
of  unmined  coal  seems  not  to  have  been  sufficiently  ap- 
preciated in  the  past,  and  that  in  the  future  it  should  be 
better  appraised  at  its  true  value  to  the  nation. 

This  question  may  be  viewed  from  another  aspect  by 
making  a  comparison  of  the  cost  of  producing  a  given 
amount  of  electrical  power  from  coal  and  from  water- 
power.  Assuming  that  one  horse-power  of  electrical 
energy  maintained  for  one  year  had  a  pre-war  value  of 
5/.  ($25),  and  that  it  requires  about  eight  tons  of  average 
coal  to  produce  it,  we  arrive  at  the  price  of  6^.  3c/.  ($1.55) 
per  ton — i.e,,  crediting  the  coal  with  half  the  cost.    The 


ENGINEERING  BEFORE  AND  AFTER  WAR    55 

capital  required  to  mine  eight  tons  of  coal  a  year  in  Eng- 
land is  difficult  to  estimate,  but  it  may  be  taken  approxi- 
mately to  be  5/.,  and  the  capital  for  plant  and  machinery 
to  convert  it  into  electricity  at  10/.,  making  a  total  of  15/. 
In  the  case  of  water-power  the  average  capital  cost  on  the 
above  basis  is  40L,  including  water  rights  (though  in  ex- 
ceptionally favored  districts  much  lower  costs  are  re- 
corded). 

From  these  figures  it  appears  that  the  average  capital 
required  to  produce  electrical  power  from  coal  is  less  than 
one-half  the  amount  that  is  required  in  the  case  of  water- 
power.  The  running  costs,  however,  in  connection  with 
water-power  are  much  less  than  those  in  respect  of  coal. 
Another  interesting  consideration  is  that  the  cost  of  har- 
nessing all  the  water-power  of  the  world  would  be  about 
8,000  millions,  or  equal  to  the  cost  of  the  war  to 
England. 

Dowling  has  estimated  the  total  coal  of  the  world  as 
over  seven  million  million  tons,  and  whether  we  appraise 
it  at  i^.  or  more  per  ton  its  present  and  prospective  value 
is  prodigious.  For  instance,  at  6s.  ^d.  per  ton  it  amounts 
to  nearly  one  hundred  times  the  cost  of  the  war  to  all  the 
belligerents. 

In  some  foreign  countries  the  capital  costs  of  mining 
are  far  below  the  figures  I  have  taken,  and,  as  coal  is 
transportable  over  long  distances  and,  generally  speak- 
ing, electricity  is  not  so  at  present,  therefore  it  seems 
probable  that  capital  will  in  the  immediate  future  flow  in 
increasing  quantity  to  mining  operations  in  foreign  coun- 
tries rather  than  to  the  development  of  the  more  difficult 
and  costly  water-power  schemes.  When,  however,  capi- 
tal becomes  more  plentiful  the  lower  running  costs  of 
water-power  will  prevail,  with  the  result  that  it  will  then 
be  rapidly  developed. 

As  to  the  possible  new  sources  of  power,  I  have  already 
mentioned  molecular  energy,  but  there  is  another  alterna- 
tive which  appears  to  merit  attention. 


56  CONTEMPORARY  SCIENCE 

Bore  Hole, — In  my  address  to  Section  G  in  1904  I  dis- 
cussed the  question  of  sinking  a  shaft  to  a  depth  of  twelve 
miles,  which  is  about  ten  times  the  depth  of  any  shaft  in 
existence.  The  estimated  cost  was  5,000,000/.,  and  the 
time  required  about  eighty-five  years. 

The  method  of  cooHng  the  air-locks  to  limit  the  baro- 
metric pressure  on  the  miners  and  other  precautions  were 
described,  and  the  project  appeared  feasible.  One  essen- 
tial factor  has,  however,  been  queried  by  some  persons: 
Would  the  rock  at  the  great  depth  crush  in  and  destroy 
the  shaft?  Subsequent  to  my  address,  I  wrote  a  letter  to 
Nature,  suggesting  that  the  question  might  be  tested  ex- 
perimentally. Professor  Frank  D.  Adams,  of  McGill  Uni- 
versity, Montreal,  acting  on  the  suggestion,  has  since  car- 
ried out  exhaustive  experiments,  published  in  the  Journal 
of  Geology  for  February,  1912,  showing  that  in  limestone 
a  depth  of  fifteen  miles  is  probably  practicable,  and  that 
in  granite  a  depth  of  thirty  miles  might  be  reached. 

Little  is  at  present  known  of  the  earth's  interior,  except 
by  inference  from  a  study  of  its  surface,  upturned  strata, 
shallow  shafts,  the  velocity  of  transmission  of  seismic 
disturbances,  its  rigidity  and  specific  gravity,  and  it  seems 
reasonable  to  suggest  that  some  attempt  should  be  made 
to  sink  a  shaft  as  deep  as  may  be  found  practicable  and 
at  some  locality  selected  by  geologists  as  the  most  likely 
to  aflFord  useful  information. 

When  we  consider  that  the  estimated  cost  of  sinking  a 
shaft  to  a  depth  of  twelve  miles,  at  present-day  prices, 
is  not  much  more  than  the  cost  of  one  day  of  the  war  to 
Great  Britain  alone,  the  expense  seems  trivial  as  com- 
pared with  the  possible  knowledge  that  might  be  gained 
by  an  investigation  into  this  unexplored  region  of  the 
earth.  It  might,  indeed,  prove  of  inestimable  value  to 
Science,  and  also  throw  additional  light  on  the  internal 
constitution  of  the  earth  in  relation  to  minerals  of  high 
specific  gravity. 

In  Italy,  at  Lardarello,  bore  holes  have  been  sunk,  which 


ENGINEERING  BEFORE  AND  AFTER  WAR    57 

discharge  large  volumes  of  high-pressure  steam,  which  is 
being  utilized  to  generate  about  10,000  horse-power  by 
turbines.  At  Solfatara,  near  Naples,  a  similar  project  is 
on  foot  to  supply  power  to  the  great  works  in  the  district. 
It  seems,  indeed,  probable  that  in  volcanic  regions  a  very 
large  amount  of  power  may  be,  in  the  future,  obtained  di- 
rectly or  indirectly  by  boring  into  the  earth,  and  that  the 
whole  subject  merits  the  most  careful  consideration. 

While  on  the  subject  of  obtaining  power,  may  I  digress 
for  a  few  moments  and  describe  an  interesting  phenome- 
non of  a  somewhat  converse  nature— ^f*^.  that  of  intense 
pressure  produced  by  moderate  forces  closing  up  cavities 
in  water. 

A  Committee  was  appointed  by  the  Admiralty  in  1916 
to  investigate  the  cause  of  the  rapid  erosion  of  the  propel- 
lers of  some  of  the  ships  doing  arduous  duties.  This  was 
the  first  time  that  the  problem  had  been  systematically 
considered.  The  Committee  found  that  the  erosion  was 
due  to  the  intense  blows  struck  upon  the  blades  of  the 
propellers  by  the  nuclei  of  vacuous  cavities  closing  up 
against  them.  Though  the  pressure  bringing  the  water  to- 
gether was  only  that  of  the  atmosphere,  yet  it  was  proved 
that  at  the  nucleus  20,000  atmospheres  might  be  pro- 
duced. 

The  phenomenon  may  be  described  as  being  analagous 
to  the  well-known  fact  that  nearly  all  the  energy  of  the 
arm  that  swings  it  is  concentrated  in  the  tag  of  a  whip. 
It  was  shown  that  when  water  flowed  into  a  conical  tube 
which  had  been  evacuated  a  pressure  of  over  140  tons 
per  square  inch  was  recorded  at  the  apex,  which  was  ca- 
pable of  eroding  brass,  steel,  and  in  time  even  the  hardest 
steel.  The  phenomenon  may  occur  under  some  conditions 
in  rivers  and  waterfalls  where  the  velocity  exceeds  50 
feet  per  second,  and  it  is  probably  as  great  a  source  of 
erosion  as  by  the  washing  down  oiF  boulders  and  pebbles. 
Then  again,  when  waves  beat  on  a  rocky  shore,  under 
some  conditions,  intense  hydraulic  pressures  will  occur, 


58  CONTEMPORARY  SCIENCE 

quite  sufficient  of  themselves  to  crush  the  rock  and  to 
open  out  narrow  fissures  into  caves. 

Research. — The  whole  question  of  the  future  resources 
of  the  Empire  is,  I  venture  to  think,  one  which  demands 
the  serious  attention  of  all  scientists.  It  should  be  at- 
tacked in  a  comprehensive  manner,  and  with  that  insist- 
ence which  has  been  so  notable  in  connection  with  the 
efforts  of  British  investigators  in  the  past.  In  such  a 
task,  some  people  might  suggest,  we  need  encouragement 
and  assistance  from  the  Government  of  the  country. 
Surely  we  have  it.  As  many  here  know,  a  great  experi- 
mental step  towards  the  practical  realization  of  Solomon's 
House  as  prefigured  by  Francis  Bacon  in  the  New  Atlan- 
tis is  being  made  by  the  Gk)vernment  at  the  present  time. 
The  inception,  constitution,  and  methods  of  procedure  of 
the  Department,  which  was  constituted  in  191 5,  were  fully 
described  by  Sir  Frank  Heath  in  his  paper  to  the  Royal 
Society  of  Arts  last  February,  and  it  was  there  stated  by 
Lord  Crewe  that,  so  far  as  he  knew,  this  was  the  only 
country  in  which  a  Government  Department  of  Research 
existed.^ 

It  is  obvious  that  the  work  of  a  Department  of  this  kind 
must  be  one  of  gradual  development  with  small  begin- 
nings, in  order  that  it  may  be  sound  and  lasting.  The 
work  commenced  by  assisting  a  number  of  researches  con- 
ducted by  scientific  and  professional  societies  which  were 
languishing  as  a  result  of  the  war,  and  grants  were  also 
made  to  the  National  Physical  Laboratory  and  to  the 
Central  School  of  Pottery  at  Stoke-on-Trent.  The  grants 
for  investigation  and  research  for  the  year  1916-17  to- 
talled 11,055/.  ($55,000),  and  for  the  present  year  are 
anticipated  to  be  93,570/.  The  total  income  of  the  Na- 
tional Physical  Laboratory  in  1913-14  was  43,713/.,  and 

^The  Italian  Government  are  now,  however,  establishing  a 
National  Council  for  Research,  and  a  Bill  is  before  the  French 
Chamber  for  the  establishment  of  a  National  Office  of  Scientific, 
Industrial,  and  Agricultural  Research  and  Inventions. 


ENGINEERING  BEFORE  AND  AFTER  WAR    59 

owing  to  the  great  enlargement  of  the  Laboratory  the 
total  estimate  of  the  Research  Department  for  this  service 
during  the  current  year  is  154,650/. 

Another  important  part  of  the  work  of  the  Department 
has  been  to  foster  and  to  aid  financially  Associations  of 
the  trades  for  the  purpose  of  research.  Nine  of  these 
Associations  are  already  at  work ;  eight  more  are  ap- 
proved, and  will  probably  be  at  work  within  the  next  two 
months;  and  another  twelve  are  in  the  earlier  stage  of 
formation.  There  are  also  signs  of  increased  research  by 
individual  factories.  Whether  this  is  due  to  the  indirect 
influence  of  the  Research  Department  or  to  a  change  in 
public  opinion  and  a  more  general  recognition  of  the  im- 
portance of  scientific  industrial  research  it  is  difficult  to 
say. 

The  possibility  of  the  uncontrolled  use  on  the  part  of  a 
nation  of  the  power  which  Science  has  placed  within  its 
reach  is  so  great  a  menace  to  civilization  *  that  the  ardent 
wish  of  all  reasonable  people  is  to  possess  some  radical 
means  of  prevention  through  the  establishment  of  some 
form  of  wide  and  powerful  control.  Has  not  Science 
forged  the  remedy,  by  making  the  world  a  smaller  arena 
for  the  activities  of  civilization,  by  reducing  distance  in 
terms  of  time?  Alliances  and  unions,  which  have  suc- 
cessfully controlled  and  stimulated  republics  of  hetero- 
geneous races  during  the  last  century,  will  therefore  have 
become  possible  on  a  wider  and  grander  scale,  thus  unit- 
ing all  civilized  nations  in  a  great  League  to  maintain 
order,  security,  and  freedom  for  every  individual  and  for 
every  State  and  nation  liberty  to  devote  their  energies  to 
the  controlling  of  the  great  forces  of  Nature  for  the  use 
and  convenience  of  man,  instead  of  applying  them  to  the 
killing  of  each  other. 

*  For  instance,  it  might  some  day  be  discovered  how  to  liberate 
instantaneously  the  energy  in  radium,  and  radium  contains  two 
and  one-half  million  times  the  energy  of  the  same  weight  of 
T.N.T. 


6o  CONTEMPORARY  SCIENCE 

Many  of  us  remember  the  President's  Banner  at  the 
Manchester  Meeting  in  191 5,  where  Science  is  allegori- 
cally  represented  by  a  sorrowful  figure  covering  her  eyes 
from  the  sight  of  the  guns  in  the  foreground.  This  year 
Science  is  represented  in  her  more  joyful  mien,  encourag- 
ing the  arts  and  industries.  It  is  sincerely  to  be  hoped 
that  the  future  will  justify  our  present  optimism. 


METHODS  OF  GAS  WARFARE 

(Report  of  a  lecture  delivered  before  the  Wash- 
ington Academy  of  Sciences  on  Jan.  17,  1918) 

BY 

S.  J.  M.  AuLD,  D.S.M. 
British  Military  Mission 

I  happened  to  be  present  at  the  first  gas  attack  and 
saw  the  whole  gas  business  from  the  beginning.  The  first 
attack  was  made  in  April,  1915.  A  deserter  had  come 
into  the  Ypres  salient  a  week  before  the  attack  was 
made,  and  had  told  us  the  whole  story.  They  were  pre- 
paring to  poison  us  with  gas,  and  had  cylinders  installed 
in  their  trenches.  No  one  believed  him  at  all,  and  no  no- 
tice was  taken  of  it. 

Then  came  the  first  gas  attack,  and  the  whole  course  of 
the  war  changed.  That  first  attack,  of  course,  was  made 
against  men  who  were  entirely  unprepared — absolutely 
unprotected.  You  have  read  quite  as  much  about  the 
actual  attack  and  the  battle  as  I  could  tell  you,  but  the 
accounts  are  still  remarkably  meager.  The  fellows  who 
could  have  told  most  about  it  didn't  come  back.  The 
Germans  have  claimed  that  we  had  6,000  killed  and  as 
many  taken  prisoners.  They  left  a  battlefield  such  as 
had  never  been  seen  before  in  warfare,  ancient  or  mod- 
ern, and  one  that  has  had  no  compeer  in  the  whole  war 
except  on  the  Russian  front. 

61 


62  COxN TEMPORARY  SCIENCE 

What  the  Germans  expected  to  accomplish  by  it  I  am 
not  sur^.  Presumably  they  intended  to  win  the  war,  and 
they  might  conceivably  have  won  it  then  and  there  if  they 
had  foreseen  the  tremendous  effect  of  the  attack.  It  is 
certain  that  they  expected  no  immediate  retaliation,  as 
they  had  provided  no  protection  for  their  own  men.  They 
made  a  clear  and  unobstructed  gap  in  the  lines,  which 
was  only  closed  by  the  Canadians,  who  rallied  on  the  left 
and  advanced,  in  part  through  the  gas  cloud  itself. 

The  method  first  used  by  the  Germans,  and  retained 
ever  since,  is  fairly  simple,  but  requires  great  preparation 
beforehand.  A  hole  is  dug  in  the  bottom  of  the  trench 
close  underneath  the  parapet,  and  a  gas  cylinder  is  buried 
in  the  hole.  It  is  an  ordinary  cylinder,  like  that  used  for 
oxygen  or  hydrogen.  It  is  then  covered  first  with  a  quilt 
of  moss,  containing  potassium  carbonate  solution,  and 
then  with  sand  bags.  When  the  attack  is  to  be  made  the 
sand  bags  and  protecting  cover  are  taken  off  the  cylinder, 
and  each  cylinder  is  connected  with  a  lead  pipe  which  is 
bent  over  the  top  of  the  parapet.  A  sand  bag  is  laid  on 
the  nozzle  to  prevent  the  back  "kick"  of  the  outrushing 
gas  from  throwing  the  pipe  back  into  the  trench.  Our 
own  methods  are  practically  identical  with  those  first  used 
by  the  Germans. 

The  success  of  a  cloud  gas  attack  depends  on  thorough 
preparation  beforehand.  The  attackers  must  know  the 
country,  the  layout  of  the  trenches,  and  the  direction  and 
velocity  of  the  wind  with  certainty.  Favorable  conditions 
are  limited  practically  to  wind  velocities  between  12  and 
4  miles  an  hour.  A  wind  of  more  than  12  miles  an  hour 
disperses  the  gas  cloud  very  rapidly.  An  upward  cur- 
rent of  air  is  the  worst  foe  of  gas.  The  weight  of  the 
gas  is  not  an  important  factor  in  carrying  it  along,  for  it 
mixes  rapidly  with  air  to  form  the  moving  "cloud."  The 
time  occupied  by  a  gas  attack  is  too  short  to  permit  of 
much  diffusion  of  the  gas  out  of  the  original  mixture. 

The  gas  attack  must  be  planned  very  carefully.    If  the 


METHODS  OF  GAS  WARFARE  6j 

trench  line  is  very  irregular  it  is  likely  that  gas  will  flovv 
into  a  portion  of  one's  own  trenches.  The  limits  oi 
safety  in  wind  direction  are  thus  determined  by  the  direc- 
tion of  the  lines  of  the  trenches.  The  Germans  use  a  40^ 
angle  of  safety ;  that  means  that  on  a  given  straight  por- 
tion of  the  front  the  wind  direction  must  lie  between  the 
two  directions  which  make  angles  of  40°  with  the  neigh-r 
boring  sections  of  the  front.  The  most  suitable  type  of 
country  is  where  the  ground  slopes  gently  away  fron^ 
where  the  gas  is  being  discharged.  The  Germans  made 
one  mistake  in  believing  that  hilly  or  wooded  country 
would  not  do.  This  was  refuted  by  the  French,  who  made 
a  successful  gas  attack  in  hilly  and  wooded  country  in 
the  Vosges,  as  admitted  in  a  captured  German  report.  If 
the  country  is  flat  like  that  about  Ypres,  and  the  wind  di- 
rection is  right,  there  is  very  little  difficulty  about  making 
an  attack,  especially  if  the  enemy  does  not  know  anything 
about  it.    The  element  of  surprise  is  important. 

German  gas  attacks  are  made  by  two  Regiments  of 
Pioneers,  with  highly  technical  officers,  including  engi- 
neers, meteorologists,  and  chemists.  They  brought  their 
first  cylinders  into  the  line  without  our  knowing  anything 
about  it,  except  from  the  deserter's  report  which  was  not 
believed.  The  element  of  surprise  was  greatly  lessened 
when  we  began  to  know  what  to  look  for  and  to 
recognize  the  sounds  incident  to  the  preparation  of  a  gas 
attack. 

The  first  attack  was  made  with  chlorine.  If  a  gas  at- 
tack is  to  be  made  with  gas  clouds,  the  number  of  gases 
available  is  limited.  The  gas  must  l3e  easily  compressible, 
easily  made  in  large  quantities,  and  should  be  considerably 
heavier  than  air.  If  to  this  is  added  the  necessity  of  its 
being  very  toxic  and  of  low  chemical  reactivity,  the  choice 
is  practically  reduced  to  two  gases:  chlorine  and  phos- 
gene. Chlorine  is  to  gas  warfare  what  nitric  acid  is  to 
high  explosives.  Pure  chlorine  did  not  satisfy  quite  all 
the  requirements,  as  it  is  very  active  chemically  and  there- 


64  CONTEMPORARY  SCIENCE 

fore  easily  absorbed.  Many  men  in  the  first  attack. who 
had  sufficient  presence  of  mind  saved  themselves  by  bury- 
ing their  faces  in  the  earth,  or  by  stuffing  their  mufflers  in 
their  mouths  and  wrapping  them  around  their  faces. 

There  were  several  gas  attacks  of  almost  exactly  the 
same  kind  early  in  191 5.  There  was  no  gas  between  the 
end  of  May,  191 5,  and  December,  191 5,  and  by  that  time 
adequate  protection  had  been  provided. 

The  first  protection  was  primitive.  It  consisted  largely 
of  respirators  made  by  women  in  England  in  response  to 
an  appeal  by  Kitchener.  They  were  pads  of  cotton  wool 
wrapped  in  muslin  and  soaked  in  solutions  of  sodium  car- 
bonate and  thiosulfate;  sometimes  they  were  soaked  only 
in  water.  A  new  type  appeared  almost  every  week.  One 
simple  type  consisted  of  a  pad  of  cotton  waste  wrapped 
up  in  muslin  together  with  a  separate  v/ad  of  cotton  waste. 
These  were  kept  in  boxes  in  the  trenches,  and  on  the  word 
"gas"  six  or  eight  men  would  make  a  dive  for  the  box, 
stuflf  some  waste  into  their  mouths,  then  fasten  on  the 
pad  and  stuff  the  waste  into  the  space  around  the  nose 
and  mouth.  But  this  got  unpopular  after  a  bit,  when  it 
was  discovered  that  the  same  bits  of  waste  were  not  al- 
.ways  used  by  the  same  men.  During  the  early  part  of 
11915  this  was  the  only  protection  used. 

Then  came  the  helmet  made  of  a  flannel  bag  soaked  in 
thiosulfate  and  carbonate,  with  a  mica  window  in  it.  A 
modified  form  of  this  device  with  different  chemicals  is 
still  used  in  the  British  army  as  a  reserve  protection.  It 
is  put  over  the  head  and  tucked  into  the  jacket,  and  is 
fool-proof  as  long  as  well  tucked  down.  This  stood  up 
very  well  against  chlorine. 

In  191 5  we  got  word  from  our  Intelligence  Department 
of  a  striking  kind.  It  consisted  of  notes  of  some  very 
secret  lectures  given  in  Germany  to  a  number  of  the 
senior  officers.  These  lectures  detailed  materials  to  be 
used,  and  one  of  them  was  phosgene,  a  gas  which  is  very 
insidious  and  difficult  to  protect  against.    We  had  to  hurry 


METHODS  OF  GAS  WARFARE  65 

up  to  find  protection  against  it.  The  outcome  was  a  hel- 
met saturated  with  sodium  phenate.  The  concentration 
of  gases  when  used  in  a  cloud  is  small,  and  i  to  1,000  by 
volume  is  relatively  very  strong.  The  helmet  easily  gave 
protection  against  phosgene  at  a  normal  concentration  of 
I  part  in  10,000.  That  helmet  was  used  when  the  next 
attack  came  in  Flanders,  on  the  19th  of  Decemlier.  This 
attack  was  in  many  ways  an  entirely  new  departure  and 
marked  a  new  era  in  gas  warfare. 

There  are  three  things  that  really  matter  in  gas  war- 
fare, and  these  were  all  emphasized  in  the  attack  of  De- 
cember. They  are:  (i)  increased  concentration;  (2) 
surprise  in  tactics;  (3)  the  use  of  unexpected  new  ma- 
terials. 

Continued  efforts  have  been  made  on  both  sides  to  in- 
crease the  concentration.  The  first  gas  attack,  in  April, 
191 5,  lasted  about  one  and  a  half  hours.  The  attack  in 
May  lasted  three  hours.  The  attack  in  December  was 
over  in  thirty  minutes.  Thus,  assuming  the  number  of 
cylinders  to  be  the  same  (one  cylinder  for  every  meter  of 
front  in  which  they  were  operating) ,  the  last  attack  real- 
ized just  three  times  the  concentration  of  the  first,  and 
six  times  the  concentration  obtained  in  May.  Other  cloud 
gas  attacks  followed,  and  the  time  was  steadily  reduced ; 
the  last  attacks  gave  only  ten  to  fifteen  minutes  for  each 
discharge.  We  believe  that  the  cylinders  are  now  put  in 
at  the  rate  of  three  for  every  two  meters  of  front,  and 
may  even  be  doubled  banked. 

The  element  of  surprise  came  in  an  attack  by  night. 
The  meteorological  conditions  are  much  better  at  night 
than  during  the  day.  The  best  two  hours  out  of  the 
twenty-four,  when  steady  and  downward  currents  exist, 
are  the  hour  between  sunset  and  dark  and  the  hour  be- 
tween dawn  and  sunrise.  Gas  attacks  have  therefore 
been  frequently  made  just  in  the  gloaming  or  early  morn- 
ing, between  lights.  This  took  away  one  of  the  easy 
methods  of  spotting  gas,  that  of  seeing  it,  and  we  bad 


66  CONTEMPORARY  SCIENCE 

to  depend  upon  the  hissing  noises  made  by  the  escaping 
gas,  and  upon  the  sense  of  smell. 

Another  element  of  surprise  was  the  sending  out  of 
more  than  one  cloud  in  an  attack.  After  the  first  cloud 
the  men  would  think  it  was  all  over,  but  ten  minutes  or 
half  an  hour  later  there  would  come  another  cloud  on 
exactly  the  same  front.  These  tactics  were  very  success- 
ful in  at  least  one  case,  namely,  the  attack  near  HuUuch 
in  1916.  Some  of  the  troops  discarded  their  helmets 
after  the  first  wave  and  were  caught  on  the  second,  which 
was  very  much  stronger  than  the  first. 

Efforts  were  also  made  to  efiPect  surprise  by  silencing 
the  gas.  But  silencers  reduced  the  rate  of  escape  so 
greatly  that  the  loss  of  efficiency  from  low  concentration 
more  than  made  up  for  the  gain  in  suddenness.  Another 
method  was  to  mix  the  gas  up  with  smoke,  or  to  alternate 
gas  and  smoke,  so  that  it  would  be  difficult  to  tell  where 
the  gas  began  and  the  smoke  ended. 

The  last  attack  made  on  the  British  by  this  means  was 
in  August,  1916.  Since  that  time  the  Germans  have  used 
gas  three  times  on  the  West  Front  against  the  French, 
and  have  also  used  it  against  the  Italians  and  the  Rus- 
sians. It  has  been  practically  given  up  against  the  British, 
although  the  method  is  by  no  means  dead. 

The  last  attack  was  a  slight  set-back  in  the  progress  of 
gas  defense.  The  casualties  had  been  brought  down  to  a 
minimum,  and,  as  shown  by  the  fact  that  the  percentage 
of  deaths  was  high,  protection  was  complete  in  all  cases 
where  used,  casualties  being  due  to  unpreparedness  in 
some  form.  The  attack  in  question  was  brought  on  under 
difficult  conditions  for  the  defenders,  as  it  was  made  on 
new  troops  during  a  relief  when  twice  as  many  men  were 
in  the  trenches  as  normally.  Furthermore,  they  had  to 
wear  helmets  while  carrying  their  complete  outfit  for  the 
relief.  This  was  the  second  time  the  Germans  caught  us 
m  a  relief,  whether  through  information  or  luck  we  can- 
not say. 


METHODS  OF  GAS  WARFARE      67 

The  protection  that  had  been  devised  against  phosgene 
proved  effective  at  the  time,  but  provision  was  made  to 
meet  increased  concentration  of  phosgene.  We  never  had 
any  actual  evidence  during  the  attack  that  phosgene  was 
being  used,  as  no  samples  were  actually  taken  from  the 
cloud,  but  cylinders  of  phosgene  were  captured  later. 
Glass  vacuum  tubes,  about  10  by  30  cm.,  with  a  tip  that 
could  be  broken  off  and  then  closed  by  a  phastlcine-llned 
glass  cap,  were  distributed,  but  the  only  one  that  came 
back  was  an  unopened  tube  found  in  a  hedge,  and  marked 
by  the  finder  "Dangerous ;  may  contain  cholera  germs."' 
In  a  gas  attack  everybody  keeps  quiet  or  else  has  a  job  on 
hand,  and  conditions  are  not  conducive  to  the  taking  of 
gas  samples.  The  original  types  of  vacuum  tube  were 
smaller  than  those  now  used. 

There  was  a  long  search  for  materials  that  would  ab- 
sorb phosgene,  as  there  are  few  substances  that  react 
readily  with  It.  The  successful  suggestion  came  from 
Russia.  The  substance  now  used  very  extensively  by  all 
is  hexamethylenetetramine  (urotropine)  (CH2)6N4,  which 
reacts  very  rapidly  with  phosgene.  Used  In  conjunction 
with  sodium  phenate,  it  will  protect  against  phosgene  at 
a  concentration  of  i :  1000  for  a  considerable  period.  An 
excess  of  sodium  hydroxide  is  used  with  the  sodium  phe- 
nate, and  a  valve  Is  provided  In  the  helmet  for  the  escape 
of  exhaled  air.  The  valve  was  originally  devised  so  that 
the  hydroxide  would  not  be  too  rapidly  carbonated,  but  it 
was  found  in  addition  that  there  Is  a  great  difference  in 
ease  of  breathing  and  comfort  If  a  valve  Is  placed  in  the 
mask.  The  helmet  is  put  on  over  the  head,  grasped  with 
left  hand  around  the  neck  and  tucked  into  the  jacket. 
This  form  Is  still  used  in  reserve. 

By  this  time  gas  shells  were  beginning  to  be  used  in 
large  numbers,  and  it  became  evident  that  protection  by  a 
fabric  could  not  be  depended  on  with  certainty.  The  box 
type  of  respirator  was  the  next  development.  Respirators 
have  to  fulfill  two  requirements  which  are  quite  opposed 


68  CONTEMPORARY  SCIENCE 

to  one  another.  In  the  first  place  they  should  be  suffi- 
ciently large  and  elaborate  to  give  full  protection  against 
any  concentration  of  any  gas,  whereas  military  exigency 
requires  that  they  be  light  and  comfortable.  It  is  neces- 
sary to  strike  a  balance  between  these  two.  Upon  a 
proper  balance  depends  the  usefulness  of  the  respirator. 
Oxygen  apparatus  will  not  do  on  account  of  its  weight 
and  its  limited  life.  Two  hours'  life  is  excessive  for  that 
type.  The  side  that  can  first  force  the  other  to  use  oxygen 
respirators  for  protection  has  probably  won  the  war. 

The  concentrations  of  gas  usually  met  with  are  really 
very  low.  As  has  been  said,  a  high  concentration  for  a 
gas  cloud  is  i  part  in  i,ooo,  whereas  concentrations  of 
two  or  three  per  cent,  can  be  met  by  respirators  depend- 
ing on  chemical  reactivity.  One  such  respirator  is  a  box 
of  chemicals  connected  by  a  flexible  tube  with  a  face- 
piece  fitting  around  the  contours  cf  the  face,  and  provided 
v^ith  a  mouthpiece  and  nosepiece. 

As  regards  the  chemicals  used  there  is  no  secret,  for 
the  Germans  have  many  of  the  same  things.  Active  ab- 
sorbent charcoal  is  one  of  the  main  reliances,  and  is  an- 
other suggestion  that  we  owe  to  the  Russians.  Wood 
charcoal  was  used  in  one  of  their  devices  and  was  effec- 
tive, but  most  of  the  Russian  soldiers  had  no  protection 
at  all. 

We  wanted  to  protect  against  chlorine,  acids  and  acid- 
iorming  gases,  phosgene,  etc.,  and  at  one  time  were  fear- 
ful of  meeting  large  quantities  of  hydrocyanic  (prussic) 
acid  (HCN).  At  one  period  every  prisoner  taken  talked 
about  the  use  of  prussic  acid,  saying  that  the  Kaiser  had 
decided  to  end  the  war  and  had  given  permission  to  use 
prussic  acid.  Protection  was  evidently  needed  against  it. 
The  three  things  that  then  seemed  most  important  were : 
(i)  chlorine  and  phosgene;  (2)  prussic  acid;  (3)  lachry- 
mators.  Charcoal  and  alkaline  permanganate  will  protect 
against  nearly  everything  used,  even  up  to  concentrations 
of  ten  per  cent,  for  short  periods. 


METHODS  OF  GAS  WARFARE      69 

The  German  apparatus,  developed  about  the  same  time^ 
is  of  different  pattern,  and  is  still  employed.  It  consists 
of  a  small  drum,  attached  directly  to  the  front  of  the 
face-piece,  and  weighs  less  than  the  British  respirator 
but  must  be  changed  more  frequently.  It  has  no  mouth- 
piece. The  chemicals  are  in  three  layers:  first  an  inside 
layer  of  pumice  with  hexamethylenetetramine,  in  the  mid- 
dle a  layer  of  charcoal  (sometimes  blood  charcoal),  and 
outside  baked  earth  soaked  in  potassium  carbonate  solu- 
tion and  coated  with  fine  powdered  charcoal. 

As  regards  the  future  of  the  gas  cloud,  it  may  be  looked 
upon  as  almost  finished.  There  are  so  many  conditions 
that  have  to  be  fulfilled  in  connection  with  it  that  its  use 
is  limited.  It  is  very  unlikely  that  the  enemy  will  be  able 
to  spring  another  complete  surprise  with  a  gas  cloud. 

The  case  is  different  with  gas  shells.  The  gas  shells  are 
the  most  important  of  all  methods  of  using  gas  on  the 
Western  Front,  and  are  still  in  course  of  development. 
The  enemy  started  using  them  soon  after  the  first  cloud 
attack.  He  began  with  the  celebrated  "tear"  shells,  A 
concentration  of  one  part  in  a  million  of  some  of  these 
lachrymators  makes  the  eyes  water  severely.  The  origi- 
nal tear  shells  contained  almost  pure  xylyl  bromide  or 
benzyl  bromide,  made  by  brominating  the  higher  frac- 
tions of  coal-tar  distillates. 

The  German  did  his  bromination  rather  badly.  As  you 
know,  it  should  be  done  very  carefully  or  much  dibromide 
is  produced,  which  is  solid  and  inactive.  Some  of  the 
shells  contained  as  much  as  20  per  cent,  dibromide,  enough 
to  make  the  liquid  pasty  and  inactive.  The  shells  used 
contain  a  lead  lining,  and  have  a  partition  across  the 
shoulder,  above  which  comes  the  T.  N.  T.  and  the  fuse. 
These  shells  had  little  effect  on  the  British,  but  one  attack 
on  the  French,  accompanied  by  a  very  heavy  bombard- 
ment with  tear  shells,  put  them  out  badly.  The  eyes  of 
the  men  were  affected,  and  many  of  the  men  were  even 
anesthetized  by  the  gas,  and  were  taken  prisoner. 


70  CONTEMPORARY  SCIENCE 

Our  first  big  experience  was  an  attack  at  Vermelles. 
The  Germans  put  down  a  heavy  barrage  of  these  shells  and 
made  an  infantry  attack.  The  concentration  was  great, 
the  gas  went  through  the  helmets,  and  the  men  even  vom- 
ited inside  their  helmets.  But  it  is  difficult  to  put  down 
a  gas  barrage,  and  there  is  danger  that  it  will  not  be  a 
technical  success.  In  the  instance  cited  certain  roads  were 
not  cut  off  sufficiently,  so  that  reinforcements  got  up. 
This  attack,  however,  opened  our  eyes  to  the  fact  that,  as 
in  the  case  of  gas  clouds,  concentration  would  be  developed 
so  as  to  make  it  high  enough  to  produce  the  required 
effect  under  any  circumstances. 

When  the  Germans  started  using  highly  poisonous 
shells,  which  was  at  the  Somme  in  191 6,  they  did  not  at- 
tend to  this  sufficiently,  although  enormous  numbers  of 
shell  were  used.  The  substance  used  was  trichloromethyl- 
chloroformate,  but  not  in  great  strength.  It  had  no  de- 
cided reaction  on  the  eyes,  hence  the  men  were  often 
caug^ht. 

The  quantity  of  gas  that  can  be  sent  over  in  shells  is 
small.  The  average  weight  in  a  shell  is  not  more  than 
six  pounds,  whereas  the  German  gas  cylinders  contain  40 
pounds  of  gas.  To  put  over  the  same  amount  of  gas  as 
with  gas  clouds,  say  in  five  minutes  per  thousand  yards  of 
front,  would  require  a  prohibitive  number  of  guns  and 
shells.  It  becomes  necessary  to  put  the  shells  on  definite 
targets,  and  this,  fortunately,  the  Germans  did  not 
realize  at  the  Somme,  although  they  have  found  it  out 
since. 

The  use  of  gas  out  of  a  projectile  has  a  number  of  ad- 
vantages over  its  use  in  a  gas  cloud.  First,  it  is  not  so 
dependent  on  the  wind.  Again,  the  gunners  have  their 
ordinary  job  of  shelling,  and  there  is  no  such  elaborate 
and  unwelcome  organization  to  put  into  the  front  trenches 
as  is  necessary  for  the  cloud.  Third,  the  targets  are 
picked  with  all  the  accuracy  of  artillery  fire.  Fourth,  the 
gas  shells  succeed  with  targets  that  are  not  accessible  to 


METHODS  OF  GAS  WARFARE      71 

high  explosives  or  to  gas  clouds.  Take,  for  instance,  a 
field  howitzer,  dug  into  a  pit  with  a  certain  amount  of 
overhead  cover  for  the  men,  who  come  in  from  behind 
the  gun.  The  men  are  safe  from  splinters,  and  only  a 
direct  hit  will  put  the  gun  out  of  action.  But  the  gas  will 
go  in  where  the  shell  would  not.  It  is  certain  to  gas  some 
of  the  men  inside  the  emplacement.  The  crew  of  the  gun 
must  go  on  firing  with  gas  masks  on,  and  with  depleted 
numbers.  Thus  it  nearly  puts  the  gun  out  of  commission, 
reducing  the  number  of  shots  say  from  two  rounds  a 
minute  to  a  round  in  two  minutes,  and  may  even  silence  it 
entirely.  Another  example  is  a  position  on  a  hillside  with 
dugouts  at  the  back,  just  over  the  crest,  or  with  a  sunken 
road  behind  the  slope.  Almost  absolute  protection  is  af- 
forded by  the  dugouts.  The  French  tried  three  times  to 
take  such  a  position  after  preparation  with  high  explos- 
ives, and  each  assault  failed.  Then  they  tried  gas  shells, 
and  succeeded.  The  gas  flows  rapidly  into  such  a  dug- 
out, especially  if  it  has  two  or  more  doors. 

Among  the  effective  materials  used  by  the  Germans  for 
gas  shells  were  mono-  and  tri-chloromethyl-chloroformate. 
Prussic  acid  never  appeared;  the  Germans  rate  it  lower 
than  phosgene  in  toxicity,  and  the  reports  concerning  it 
were  obviously  meant  merely  to  produce  fear  and  distract 
the  provisions  for  protection. 

During  the  last  five  months  the  actual  materials  and 
the  tactics  used  by  the  Germans  have  undergone  a  com- 
plete change.  The  lachrymator  shells  are  less  depended 
upon  than  formerly  for  "neutralization,"  but  are  still  a 
source  of  annoyance.  Mere  annoyance,  however,  may  be 
an  effective  method  of  neutralizing  infantry.  For  in- 
stance, where  large  amounts  of  supplies  and  ammunition 
are  being  brought  up  there  are  always  cross-roads  where 
there  is  confusion  and  interference  of  trafHc.  A  few  gas 
shells  placed  there  make  every  man  put  on  his  mask,  and 
if  it  is  a  dark  night  and  the  roads  are  muddy  the  resulting 
confusion  can  be  only  faintly  imagined.     It  may  thus  be 


72  CONTEMPORARY  SCIENCE 

possible  to  neutralize  a  part  of  the  infantry  by  cutting 
down  their  supplies  and  ammunition. 

The  use  of  a  gas  shell  to  force  a  man  to  put  on  his  mask 
is  practically  neutralization.  If  at  the  same  time  you  can 
hurt  him,  so  much  the  better.  Hence  the  change  in  gas- 
shell  tactics,  which  consists  in  replacing  the  purely  lachry- 
matory substance  by  one  that  is  also  poisonous. 

One  substance  used  for  this  method  of  simultaneously 
harassing  and  seriously  injuring  was  dichloro-diethylsul- 
fide  (mustard  gas).  Its  use  was  begun  in  July  of  last 
year  at  Ypres,  and  it  was  largely  used  again  at  Nieuport 
and  Armentieres.  A  heavy  bombardment  of  mustard-gas 
shells  of  all  calibers  was  put  on  these  towns,  as  many  as 
50,000  sliells  being  fired  in  one  night.  The  effects  of 
mustard  gas  are  those  of  a  "super-lachrymator."  It  has 
a  distinctive  smell,  rather  like  garlic  than  mustard.  It 
has  no  immediate  effect  on  the  eyes,  beyond  a  slight  irri- 
tation. After  several  hours  the  eyes  begin  to  swell  and 
inflame  and  practically  bhster,  causing  intense  pain,  the 
nose  discharges  freely,  and  severe  coughing  and  even 
vomiting  ensue.  Direct  contact  with  the  spray  causes 
severe  blistering  of  the  skin,  and  the  concentrated  vapor 
penetrates  through  the  clothing.  The  respirators  of  course 
do  not  protect  against  this  blistering.  The  cases  that  went 
to  the  hospitals,  however,  were  generally  eye  or  lung 
cases,  and  blistering  alone  took  back  very  few  men. 
Many  casualties  were  caused  by  the  habit  that  some  of  the 
men  had  fallen  into  of  letting  the  upper  part  of  the  mask 
hang  down  so  as  not  to  interfere  with  seeing.  The  Ger- 
mans scored  heavily  in  the  use  of  this  gas  at  first.  It  was 
another  example  of  the  element  of  surprise  in  using  a 
new  substance^  that  produces  new  and  unusual  symptoms 
in  the  victims. 

Up  to  the  present  time  there  had  been  no  material 
brought  out  on  either  side  that  can  be  depended  on  to  go 
through  the  other  fellow^s  respirator.  The  casualties  are 
due  to  surprise  or  to  lack  of  training  in  the  use  of  masks. 


METHODS  OF  GAS  WARFARE  73 

The  mask  must  be  put  on  and  adjusted  within  six  sec- 
onds, which  requires  a  considerable  amount  of  preHminary 
training,  if  it  is  to  be  done  under  field  conditions. 

Among  other  surprises  on  the  part  of  the  Germans  were 
phenylcarbylamine  chloride,  a  lachrymator,  and  diphenyl- 
chloroarsine,  or  "sneezing  gas."  The  latter  is  mixed  in 
with  high  explosive  shells  or  with  other  gas  shells,  or  with 
shrapnel.  It  was  intended  to  make  a  man  sneeze  so  badly 
that  when  he  puts  on  his  mask  he  is  not  able  to  keep  it  on. 
The  sneezing  gas  has,  however,  not  been  a  very  great 
success. 

All  bombardments  now  are  of  this  mixed  character. 
The  shells  used  are  marked  with  differently  colored! 
crosses,  and  definite  programs  are  laid  down  for  the  use 
of  the  artillerymen. 

As  regards  the  future  of  gas  shells,  it  should  be  em- 
phasized that  the  "gas  shell"  is  not  necessarily  a  gas  shell 
at  all,  but  a  liquid  or  solid  shell,  and  it  opens  up  the 
whole  sphere  of  organic  chemistr}^  to  be  drawn  upon  for 
materials.  The  material  placed  inside  the  shell  is  trans- 
formed into  vapor  or  fine  droplets  by  the  explosion  and 
a  proper  adjustment  between  the  bursting  charge  and  the 
poisonous  substance  is  necessary.  Both  sides  are  busy 
trying  to  find  something  that  the  others  have  not  used, 
and  both  are  trying  to  find  a  "colorless,  odorless,  and  in- 
visible" gas  that  is  highly  poisonous.  It  is  within  the 
realm  of  possibilities  that  the  war  will  be  finished,  liter- 
ally, in  the  chemical  laboratory. 

The  Germans  have  not  altered  their  type  of  respirator 
for  some  time,  and  it  is  not  now  equal  in  efficiency  to  the 
British  or  American  respirator.  The  German  respirator, 
even  in  its  latest  form,  will  break  down  at  a  concentration 
of  0.3  per  cent,  of  certain  substances.  The  German  de- 
sign has  given  more  weight  to  military  exigency,  as  against 
perfect  protection,  than  has  the  British.  Another  thing 
that  weighs  against  changes  in  design  is  the  fact  that  the 
German,  already  handicapped  by  the  lack  of  certain  mate- 


74  CONTEMPORARY  SCIENCE 

rials,  must  manufacture  40,ooo,cxx)  respirators  a  year  in 
order  to  supply  his  Austrian,  Bulgarian,  and  Turkish 
allies,  as  well  as  his  own  army. 

In  the  British  and  American  armies  the  respirator  must 
always  be  carried  with  the  equipment  when  within  12 
miles  of  the  front.  Between  12  and  5  miles  a  man  may 
remove  the  respirator  box  in  order  to  sleep,  but  within  5 
miles  he  must  wear  it  constantly.  Within  2  miles  it  must 
be  won  constantly  in  the  "alert"  position  (slung  and  tied 
in  front) .  When  the  alarm  is  given  he  must  get  the  res- 
pirator on  within  six  seconds.  The  American  respirator 
Is  identical  with  the  British.  The  French  have  a  fabric 
mask  made  in  several  layers,  the  inner  provided  with  a 
nickel  salt  to  stop  HCN,  then  a  layer  with  hexamethy- 
lenetetramine ;  it  has  no  valve  and  is  hot  to  wear.  The 
French  also  use  a  box  respirator,  consisting  of  a  metal 
box  slung  on  the  back,  with  a  tube  connecting  to  the  face 
mask ;  the  latter  is  of  good  Para  rubber  and  is  provided 
with  a  valve.  One  disadvantage  of  this  form  is  the  dan- 
ger of  tearing  the  single  rubber  sheet.  The  German  mask 
now  contains  no  rubber  except  one  washer ;  the  elastics 
consist  of  springs  inside  a  fabric,  and  the  mask  itself  is 
of  leather.  It  hardens  and  cracks  after  being  wet,  and  is 
too  dependent  upon  being  well  fitted  to  the  face  when 
made. 

The  following  compounds  have  been  used  by  the  Ger- 
mans in  gas  clouds  or  in  shells : 

1.  Allyl-iso-thiocyanate  (Allyl  mustard  oil),  C3H5NCS 
(shell). 

2.  Benzyl  bromide,  CeHgCHaBr  (shell). 

3.  Bromo-acetone,  CH2Br.CO.CH3  (hand  grenades). 

4.  Bromated  methyl-ethyl-ketone  (bromo-ketone),  CHg- 
BrCOC^Hg  or  CH,.CO.CHBr.  CH3  (shell).  Dibromo- 
ketone,  CH3COCHBr.CH2Br  (shell). 

5.  Bromine,  Br2  (hand  grenades). 

6.  Chloro-acetone,  CH2CI.COCH3   (hand  grenades). 

7.  Chlorine,  CI2  (cloud). 


METHODS  OF  GAS  WARFARE  75 

8.  Chloromethyl-chloroformate   (Palite),  ClCOOCHg- 
a  (shell). 

9.  Nitro-trichloro-methane     (Chloropicrin     or     nitro- 
chloroform),  CCI3NO2  (shell). 

10.  Chlorosulfonic  acid,  SO3.H.CI  (hand  grenades  and 
"smoke  pots"). 

11.  Dichloro-diethylsulfide    (mustard    gas),     (CHgCl- 
0H2)2S  (shell). 

12.  Dimethyl  sulfate,  (CH3)2S04  (hand  grenades). 

13.  Diphenyl-chloro-arsine,   (CgHg^gAsCl   (shell). 

14.  Dichloromethyl  ether,  (CHgCOaO  (shell). 

15.  Methyl-chlorosulfonate,    CH3CISO3     (hand    gren- 
ades). 

16.  Phenyl-carbylamine  chloride,   CgHsNCClg    (shell). 

17.  Phosgene   (carbonyl  chloride),  COQ2   (cloud  and 
shell). 

18.  Sulfur  trioxide,  SO3  (hand  grenades  and  shell). 

19.  Trichloromethyl-chloro formate  (Diphosgene,  super^ 
palite),  CICOOCCI3  (shell). 

20.  Xylyl  bromide   (tolyl  bromide),   CHgCeH^CHgBr. 
(shell). 


WHAT  ARE  ENZYMES? 

BY 

Benjamin  Harrow 

The  word  enzyme  comes  from  a  Greek  word  meaning 
**in  yeast"  (en,  in;  jsyme,  leaven).  Perhaps  the  most  ac- 
ceptable definition  in  the  light  of  recent  scientific  research 
is  to  say  that  it  is  a  substance  showing  the  properties  of  a 
catalyst  and  produced  as  a  result  of  cellular  activity. 

But  what  is  a  catalyst?  The  reader  will  recall  his  first 
very  simple  experiment  in  the  preparation  of  oxygen. 
Here  the  learned  instructor  tells  the  bewildered  youth  that 
if  you  put  a  little  potassium  chlorate  in  a  test  tube  and 
heat  this  very  strongly,  a  gas  is  evolved  which  is  later 
identified  as  oxygen.  Now  by  merely  adding  a  small 
quantity  of  a  dirty  black-looking  powder,  called  man- 
ganese dioxide,  to  the  potassium  chlorate,  the  oxygen  is 
evolved  much  more  rapidly  and  at  a  much  lower  tempera- 
ture. But  this  is  not  all.  A  careful  examination  at  the 
end  of  the  reaction  shows  that  the  manganese  dioxide  has 
not  changed  in  any  way :  we  have  the  same  substance,  and 
the  same  amount  of  substance,  at  the  end  of  the  reaction 
as  at  the  beginning.  Many  such  substances  are  known  to 
chemists.  They  all  have  this  peculiarity :  that  they  acceler- 
ate chemical  reactions,  and  that  a  relatively  small — at  times 
insignificant — quantity  of  the  catalyst  suffices  to  bring 
about  the  chemical  change. 

In  cells  we  find  substances  of  this  type,  but  thus  far 
these  cellular  catalysts,  unlike  the  manganese  dioxide,  and 
like  proteins,  have  never  been  produced  outside  of  the  cell. 

76 


WHAT  ARE  ENZYMES?  77 

When  we  consider  that  hfe  is  possible  only  because  of 
continued  cellular  activity,  and  when  we  bear  in  mind  that 
this  activity  is  largely  the  result  of  chemical  changes 
brought  about  by  these  enzymes,  the  paramount  impor- 
tance of  these  substances  becomes  manifest. 

Alcoholic  fermentation  in  yeast,  the  souring  of  milk, 
processes  of  putrefaction,  and  various  other  examples  of 
changes  in  organic  materials  with,  often  enough,  the  ac- 
companying liberation  of  bubbles  of  gas,  had  long  been 
known.  The  epoch-making  researches  of  Pasteur  had 
shown  that  fermentations  and  putrefactions  were  inaugu- 
rated by  the  presence  of  living  organisms.  Then  later  ex- 
tracts from  the  saliva  and  the  gastric  mucosa  of  the  stom- 
ach were  obtained  which  also  had  the  power  of  bringing 
about  chemical  changes  in  carbohydrates  and  proteins. 
This  led  to  the  classification  of  ferments  into  those  which, 
like  yeast  and  certain  bacteria,  acted  because  of  certain 
vital  processes  (organized  ferments),  and  those  which, 
like  the  extracts  from  the  saliva  and  stomach,  were  pre- 
sumably ''non-living  unorganized  substances  of  a  chemi- 
cal nature"  (unorganized  ferments).  Kiihne  designated 
the  latter  "enzymes."  This  classification  was  generally 
accepted,  and  the  "vitalists"  held  absolute  sway  until  Emil 
Buchner,  in  1897,  overthrew  the  whole  theory  by  a  series 
of  researches  which,  in  their  influence,  were  only  second 
in  importance  to  those  of  Pasteur  in  an  earlier  genera- 
tion. One  of  Buchner's  classical  experiments  consisted 
in  grinding  yeast  cells  with  sand  and  infusorial  earth,  and 
then  subjecting  the  finely  pulverized  material  to  a  pres- 
sure of  300  atmospheres — ^a  pressure  far  more  than 
enough  to  destroy  yeast,  or  any  other  cells.  The  liquid 
so  obtained  had  all  the  fermentative  properties  of  the 
living  yeast  cell.  Obviously,  then,  the  living  cell  could 
not  be  responsible  for  the  fermentation.  On  the  other 
hand,  this  experiment  did  suggest  that  cellular  activity 
gives  rise  to  some  substance  which,  once  produced,  exerts 
its  influence  whether  the  cell  is  alive  or  dead.    All  subse- 


78  CONTEMPORARY  SCIENCE 

quent  experiments  have  but  strengthened  the  conviction 
that  cells  do  produce  these  substances,  and  that  the  chemi- 
cal changes  are  due  not  to  the  living  organisms,  but  to  the 
lifeless  substances  (enzymes)  to  which  these  organisms 
give  rise. 

Minute  in  quantity,  and  tenaciously  adhering  to  sub- 
stances present,  particularly  protein,  the  isolation  of  an 
enzyme  in  the  pure  state  has  become  one  of  the  most 
difficult  problems  in  physiological  chemistry.  Yet  any 
elementary  student  in  the  subject  finds  little  difficulty  in 
performing  simple  experiments  which  convince  him  either 
of  its  presence  or  of  its  absence.     How  are  they  done? 

The  method  consists  essentially  in  making  use  of  the 
so-called  "specificity"  of  enzymes.  To  use  Fischer's 
simile,  just  as  one  key  fits  one  lock,  so  any  one  enzyme 
will  act  on  only  a  certain  type  of  substance.  Take,  for 
example,  the  enzyme  found  in  saliva,  ptyalin:  it  readily 
acts  on  the  carbohydrate,  starch,  but  has  absolutely  no 
action  on  protein.  Again,  take  the  pepsin  of  the  stomach : 
this  enzyme  breaks  down  proteins,  but  is  without  result 
on  carbohydrates.  These  instances  may  be  multiplied  in- 
definitely. 

Some  enzymes  show  their  specificity  to  an  even  more 
marked  degree.  In  the  yeast  cell,  for  example,  we  find 
one,  sucrase,^  which  acts  only  on  cane  sugar  (sucrose)  ; 
but  on  no  other  sugar  or  carbohydrate.  A  simple  little 
experiment  demonstrates  this  beyond  question.  A  yeast 
cake  is  groimd  up  very  intimately  with  a  little  sand  and 
water,  and  the  mass  filtered.  A  small  portion  of  the  fil- 
trate is  added  to  a  solution  of  cane  sugar,  the  mixture 
placed  in  an  incubator  kept  at  38°  C,  and  allowed  to  re- 
main there  for  about  30  minutes  or  so.  At  the  end  of 
that  time  the  mixture,  if  heated  with  Fehling's  solution,^ 

^The  ending  "ase"  denotes  enzyme. 

2  This  is  the  well-known  alkaline  copper  solution  used  by  all 
medical  men  to  test  for  sugar  in  the  urine.  The  sugar  in  the 
urine  is  not,  as  might  be   supposed,  ordinary  cane   sugar,  but 


WHAT  ARE  ENZYMES?  79 

will  yield  a  red-brick  precipitate — a  result  which  could 
not  be  obtained  either  with  the  cane  sugar,  or  with  the 
enzyme  solution  alone.  No  other  carbohydrate  solution 
—or  protein,  or  fat  solution,  for  that  matter — can  take 
the  place  of  the  cane  sugar;  our  enzyme  will  be  without 
effect.  If  we  take  our  original  yeast  extract,  and  first 
heat  it  to,  say,  the  boiling  point  of  water,  then  cool  it,  and 
from  here  on  repeat  the  experiment  as  before,  no  grape 
sugar  is  obtained.  If  instead  of  heating  the  enzyme  solu- 
tion, we  cool  it,  the  action  is  considerably  delayed. 

Some  of  the  yeast  extract  may  be  poured  into  an  ex- 
cess of  alcohol,  the  precipitate  separated  by  filtration,  and 
redissolved  in  water.  This  solution  will  show  all  the 
properties  of  the  yeast  extract. 

Evidently,  then,  the  watery  extract  of  yeast  contains 
something  which  has  the  power  of  breaking  down  cane 
sugar.  This  something  is  exceedingly  sensitive  to  heat, 
rather  less  so  to  cold,  and  is  precipitated — together  with 
other  substances  (as  could  be  shown) — ^by  alcohol.  The 
last  three  properties  are  characteristic  not  only  of  sucrase, 
but  of  all  enzymes  to  a  greater  or  less  degree.  That  a 
minute  quantity  of  enzyme  can  act  upon  an  exceedingly 
large  quantity  of  substrate  is  also  readily  demonstrable. 
The  laws  of  catalysis  hold  firm. 

One  other  fact  about  enzymes  is  most  important.  Gra- 
ham, as  far  back  as  1861,  found  that  certain  substances 
(cane  sugar,  salt,  etc.)  in  solution,  when  placed  in  a  dialy- 
zer  consisting  of  a  parchment  bag,  which  in  its  turn  was 
surrounded  by  water,  would  diffuse  through  the  bag, 
whereas  others  (proteins,  gum,  starch,  etc.)  would  not. 
The  diffusible  ones  he  named  crystalloids,  those  non-dif- 
fusible, colloids.  If  some  of  our  original  yeast  extract 
were  placed  in  such  a  parchment  bag,  none  of  the  enzyme 

grape  sugar.  Fehling's  solution  reacts  with  the  latter,  but  not 
with  the  former. 

The  cane  sugar  is  split  or  "hydrolyzed,"  by  the  sucrase,  one  of 
the  products  being  grape  sugar. 


8o  CONTEMPORARY  SCIENCE 

would  find  its  way  into  the  surrounding  layer  of  water. 
Enzymes,  like  the  proteins,  are  colloids. 

The  fact  that  enzymes  show  colloidal  properties,  and 
the  fact  that  they  are  invariably  associated  with  proteins, 
made  it  seem  probable  that  when  ultimately  isolated  in 
the  pure  condition,  they  would  be  found  to  be  proteins. 
Attempts  to  obtain  pure  enzymes  have  been  many.  The 
general  method  of  procedure  in  almost  all  cases  consists 
in  first  extracting  with  water  ^ — as  already  explained — or 
submitting  the  mass  to  much  pressure  (Buchner),  if  the 
enzymes  are  "intracellular." 

Having  obtained  a  solution,  the  next  step  is  often  that 
of  dialysis  (Graham).  Diflfusible  bodies,  particularly  in- 
organic substances,  are  thereby  separated.  Three  of  the 
classical  investigators  in  this  branch,  Osborne,  Peckel- 
haring,  and  Fraenkel,  have  all  employed  this  method. 

Now  usually  comes  precipitation.  Some  substance — 
alcohol,  acetone,  or  ammonium  sulphate — is  added  in 
which  the  enzyme  is  insoluble.  The  precipitate  so  obtained 
contains  many  impurities  (proteins,  certain  carbohydrates, 
etc.).  To  purify  it,  it  is  redissolved,  re-dialyzed,  and  re- 
precipitated  many  times.  On  occasion,  a  biological  pro- 
cedure, first  suggested  by  Eflfront,  and  put  into  practice 
by  Fraenkel,  may  be  used.  This  consists  in  fermenting 
the  impure  precipitate  with  yeast.  The  carbohydrate  and 
protein  are  thereby  used  up,  but  according  to  Fraenkel,  the 
enzyme  is  not  touched. 

The  laboriousness  of  such  an  operation  may  best  be 
gathered  from  a  specific  example.  Let  us  take  an  experi- 
ment from  the  work  of  Professor  Sherman,  of  Columbia, 
an  active  investigator.  Here  is  his  method  for  preparing 
a  starch-splitting  enzyme  from  the  pancreas:  Mix  thor- 
oughly 20  grammes  of  pancreative  powder — a  commercial 
preparation — with  200  cubic  centimeters  of  50  per  cent, 
alcohol  at  15-20°  C.     [S.  finds  that  much  of  the  contained 

s  Often  containing  alcohol,  toluene,  or  chloroform  (as  pre- 
servatives). 


WHAT  ARE  ENZYMES?  8i 

protein  is  left  behind  by  the  use  of  this  50  per  cent, 
alcohol.]  Allow  this  preparation  to  stand  5-10  minutes, 
then  filter,  keeping  the  temperature  below  20°  C.  (This 
takes  from  i  to  2  hours.)  Pour  the  filtrate  into  7  times 
its  volume  of  a  mixture  of  i  part  of  alcohol  to  4  parts 
ether  (more  protein  and  other  impurities  are  here  sep- 
arated). Within  10-15  minutes  the  enzyme  (including 
certain  impurities)  separates  as  an  oily  solution.  Decant 
the  supernatant  liquid.  Dissolve  the  precipitate  in  the 
smallest  amount  of  pure  water  at  a  temperature  of  10-15 
degrees  Centigrade  and  reprecipitate  at  once  by  pouring 
into  5  volumes  of  absolute  alcohol.  Allow  it  to  settle, 
keeping  temperature  low ;  filter,  dissolve  in  200-250  cubic 
centimeters  of  50  per  cent,  alcohol  containing  5  grammes 
of  maltose.  Pour  the  solution  into  a  collodion  sack  of  500 
cubic  centimeters  capacity,  and  dialyze  against  2,000  cubic 
centimeters  of  50  per  cent,  alcohol  at  not  above  20**  C, 
and  preferably  not  below  15°  C.  Replace  dialyzate  twice: 
after  15  hours  and  a  second  period  of  8-9  hours  with 
fresh  50  per  cent,  alcohol.  Continue  dialysis  40-42  hours. 
Filter.  Pour  clear  filtrate  into  an  equal  volume  of  a 
mixture  of  alcohol  and  ether  (equal  parts).  Filter  in  the 
cold,  and  place  the  precipitate  in  a  vacuum  desiccator.* 
The  powder  obtained  is  so  active  that  it  can  digest  20,000 
times  its  own  weight  of  starch.  And  still  we  are  not  at 
all  certain  that  this  is  an  enzyme  uncontaminated  with 
foreign  bodies! 

Of  the  three  or  four  representative  workers  in  attempts 
to  isolate  a  pure  enzyme,  the  substances  obtained  by  Pro- 
fessor Sherman  and  Dr.  Osborne  (of  the  Connecticut  ex- 
periment station)  showed  decided  protein  characteristics ; 
whereas  the  two  German  investigators,  Lentner  and 
Fraenkel,  both  agree  in  proclaiming  their  products  as 
carbohydrate  in  nature.  How  near  or  how  far  from  the 
truth  is  either  group?    To  begin  with,  no  proof  that  any 

*A  vessel  (containing  a  hygroscopic  substance  to  take  up 
moisture)  from  which  thq  air  has  been  exhausted. 


82  CONTEMPORARY  SCIENCE 

of  these  products  is  loo  per  cent,  pure  has  been  advanced, 
and  the  chemist  through  bitter  experience  knows  the  dan- 
ger in  discussing  the  composition  of  impure  substances. 
Another  fact  to  be  kept  in  mind  is  that,  often  enough, 
the  purer  the  enzyme,  the  less  active  does  it  become.  In 
several  of  these  cases  it  has  been  shown  that  a  loss  in 
activity  goes  hand  in  hand  with  a  proportional  loss  in  the 
phosphoric  acid  content  of  the  substance.  This  gives  rise 
to  the  possibility — expounded  further  on — that  the  enzyme 
is  not  a  chemical  individual,  but  consists  of  at  least  two 
substances:  (a)  a  something  which  has  the  power  of  act- 
ing only  when  activated — ^in  this  instance — by  (b)  phos- 
phoric acid.  And  yet,  if  arguing  by  analogy  is  at  all 
permissible,  it  may  be  maintained  that  since  all  the  in- 
organic catalysts  are  distinct  chemical  individuals,  why 
not  enzymes  ? 

Of  course,  all  this  does  not  at  all  exclude  the  possibility 
that  different  enzymes  may  have  different  structures  and 
the  conflicting  results  of  investigators  may  be  due  to  this 
fact.  Some  of  the  men  worked  on  amylases  (starch-split- 
ting enzymes),  others  on  lipases  (fat-splitting),  others 
still  on  proteases  (protein-splitting).  Why  assume  that 
such  diverse  substances  should  all  have  the  identical  com- 
position? It  may  be,  as  Professor  Armstrong  has  sug- 
gested, that  the  enzyme  in  constitution  is  similar  to  the 
substance  on  which  it  acts. 

Extremely  suggestive  as  the  basis  for  much  present-day 
activity  has  been  the  work  of  Professor  Gabriel  Bertrand, 
of  the  Sorbonne,  Paris.  Most  of  this  has  been  on  laccase, 
an  oxidizing  enzyme  first  found  in  the  milky  latex  of  the 
tree  Rhus  vernicifera,  and  since  then  in  many  plants.  The 
production  of  the  beautiful  Japanese  lacquer  from  the 
latex  of  Rhus  vernicifera  was  shown  to  be  due  to  the 
activation  of  the  atmospheric  oxygen  by  the  laccase 
(hence  its  name).  Bertrand  was  able  to  prove  that  the 
activity  of  the  laccase  was  connected  with  the  manganese 
present,  for  by  repeated  precipitation  with  alcohol,  he  di- 


WHAT  ARE  ENZYMES?  83 

vided  his  laccase  preparations  into  three  fractions  of  dif- 
ferent manganese  content,  each  with  an  activity  distinctly 
proportional  to  the  amount  of  manganese  present.  As 
further  proof  of  the  importance  of  this  manganese,  he 
was  able  to  show  that  a  minute  addition  of  a  salt  of  man- 
ganese (manganese  sulphate)  increased  the  activity  of 
the  laccase,  whereas  other  metals  had  no  such  effect. 
This  led  him  to  the  dual  conception  of  an  enzyme,  also 
advocated  by  Armstrong:  one  of  the  constituents  is  ca- 
pable of  producing,  to  a  slight  degree,  on  its  own  account, 
the  chemical  reaction  associated  with  the  particular  enzyme 
in  question,  but  requires  its  activity  to  be  augmented  by 
the  presence  of  another  substance — inactive  in  itself — 
before  its  action  becomes  appreciable.  The  former  may 
consist  of  acid,  alkali,  calcium  or  magnesium  salt,  etc. 
The  latter  component  is  more  complex,  usually  protein- 
like (egg-white,  for  example),  and  colloidal. 

Bertrand's  views — perhaps,  also,  Fischer's  colossal  work 
on  the  synthesis  of  proteins  from  amino  acids — has  led 
the  school  of  enzyme  chemistry  to  shift  its  ground  con- 
siderably. Why  these  laborious,  and  always  futile  at- 
tempts to  isolate  a  pure  enzyme  from  the  cell  ?  Why  not 
attempt  to  synthesize  one  from  simple  inorganic  and 
organic  materials?  Trillat,  in  1904,  prepared  a  mixture 
of  traces  of  manganese  chloride  and  egg  albumen  which 
showed  the  reaction  of  laccase  and  other  oxidases  (oxi- 
dizing enzymes)  :  it  blued  guaiacum,  its  action  was  pre- 
vented by  heat  and  acid,  and  it  could  be  precipitated  by 
alcohol,  and  redissolved  in  water  without  losing  its  oxi- 
dizing powers — characteristic  properties  of  all  enzymes. 
Wolf  with  his  colloidal  iron  compounds,  and  Euler  and 
Bolin  with  their  calcium  salts  of  organic  acids  (citric, 
malic,  etc.),  and  many  others,  have  produced  strong  evi- 
dence in  favor  of  the  view  that  many  of  the  enzymes,  at 
least  many  of  the  so-called  oxidases,  are  relatively  simple 
substances. 

Along  somewhat  modified  lines  is  the  work  of  Panzer, 


84  CONTEMPORARY  SCIENCE 

who  claims  that  various  carbohydrates  show  distinct  dias- 
tatic  (carbohydrate-splitting)  activity  when  heated  with 
hydrochloric  acid  gas,  and  then  ammonia;  and  that  of 
Woker,  whose  findings,  at  present  rather  disputed,  would 
tend  to  the  belief  that  formaldehyde  (the  "formalin"  of 
commerce)  may,  under  certain  conditions,  act  in  place  of 
diastase  in  hydrolyzing  starch. 

1  Some  very  far-reaching  possibilities  are  suggested  by 
the  studies  on  the  lipases  (fat-splitting  enzymes)  of  cas- 
tor and  soya  beans  by  Dr.  Falk,  of  the  Harriman  Research 
Laboratory.  Every  worker  in  the  field  is  aware  how  very 
easily  enzymes  are  inactivated  or  destroyed  by  heat  or 
the  presence  of  relatively  small  quantities  of  certain  for- 
eign bodies,  such  as  acids  and  bases.  The  inactivation  of 
the  lipases  of  the  beans  could  be  brought  about  not  only 
by  these  means,  but  also  by  neutral  salts,  alcohol,  acetone, 
etc.  Dr.  Falk  conceived  the  idea  that  this  inactivation  was 
due  to  an  internal  rearrangement  of  certain  of  the  atoms 
in  the  molecule  of  the  enzyme.  Many  cases  of  such 
tautomeric  changes — of  rearrangement  within  the  mole- 
cule— are  known  to  organic  chemists,  and  are  often 
brought  about  by  the  action  of  mild  chemical  agents.  Dr. 
Falk's  hypothesis  is  to  the  effect  that  the  grouping  in- 
volved is  to  be  found  in  all  proteins,  and  hence,  probably, 
in  enzymes.  If  inactivation  means  the  rearrangement  of 
a  group  from  configuration  i  to  that  of  2,  activation,  or 
change  from  2  back  to  i,  may  be  brought  about  by  the 
action  of  dilute  alkali — often  used  to  bring  about  these 
changes  in  configuration.  Actual  experiments  on  the  ac- 
tion of  alkali  on  proteins  (themselves  quite  inactive)  have 
endowed  these  substances  with  fat-splitting  power. 

Whilst,  therefore,  we  are  far  from  a  comprehensive 
knowledge  of  the  chemical  configuration  of  an  enzyme, 
studies  on  the  production  of  artificial  enzymes,  and  on 
the  possible  rearrangements  of  certain  groups  within  the 
molecule,  may  throw  much  light  on  a  very  perplexing 
problem. 


NATURAL  DEATH  AND  THE  DURATION 
OF  LIFE 

BY 

Jacques  Loeb 
The  Rockefeller  Institute  for  Medical  Research 

I 

The  efforts  to  prolong  life  have  resulted  in  a  diminu- 
tion of  the  chances  of  premature  death.  Nations  with 
adequately  developed  facilities  for  medical  research  and 
an  efficient  public  health  service  have  practically  elimi- 
nated smallpox  and  typhoid,  yellow  fever  and  malaria, 
and  have  conquered  rabies,  diphtheria,  tetanus,  and  cere- 
brospinal meningitis.  If  this  development  continues  to 
receive  the  support  it  deserves,  the  time  is  bound  to  come 
when  each  human  being  can  be  guaranteed  with  a  fair 
degree  of  probability  a  full  duration  of  life.  But  why 
must  we  die  ? 

The  French  encyclopedists  of  the  eighteenth  century 
defined  life  as  that  which  resists  death.  What  they  meant 
by  this  definition  was  the  fact  that  as  soon  as  death  sets 
in,  the  body  begins  to  disintegrate.  They  argued  cor- 
rectly that  the  forces  of  disintegration  were  inherent  in 
the  living  body  but  were  held  in  check  during  life.  Re- 
cent progress  in  physical  chemistry  permits  us  to  state 
that  the  spontaneous  disintegration  of  the  body  which 
sets  in  with  death  (at  the  proper  temperature  and  proper 
degree  of  moisture)  is  a  process  of  digestion,  comparable 

85 


86  CONTEMPORARY  SCIENCE 

to  that  which  the  meat  we  eat  undergoes  in  our  stomach 
and  intestine.  The  essential  feature  of  digestion  is  in  this 
case  the  transformation  of  the  solid  meat  into  soluble 
products  by  two  ferments,  pepsin,  which  exists  in  the 
stomach,  and  trypsin,  which  exists  in  the  intestine.  The 
successive  treatment  of  meat  by  the  two  ferments  results 
in  the  breaking-up  of  the  large  insoluble  molecules  into 
the  small  soluble  molecules  of  amino  acids  which  are  ab- 
sorbed by  the  blood  and  carried  to  the  cells  of  the  body 
where  they  are  utilized  to  build  up  new  solid  cell  matter. 

These  two  ferments,  pepsin  and  trypsin,  exist  not 
only  in  the  digestive  organs,  but  in  many,  and  possibly  in 
all  living  cells,  and  the  question  arises,  why  they  do  not 
constantly  digest  and  thus  destroy  our  body  while  life 
lasts.  A  tentative  answer  to  this  question  has  been  given 
by  Dernby,  who  has  been  able  to  show  that  the  cooperation 
of  both  ferments  is  required  in  the  same  cell  for  the  work 
of  destruction,  and  that  this  cooperation  of  both  ferments 
becomes  possible  only  at  a  certain  degree  of  acidity,  which 
cannot  be  reached  in  the  living  body  on  account  of  the 
constant  removal  of  acid  through  respiration  and  oxida- 
tion. When  respiration  ceases,  the  degree  of  acidity 
necessary  for  tKe  digestive  action  of  both  ferments  in  the 
same  cell  is  reached,  leading  to  gradual  digestion  and 
liquefaction  of  the  tissues  which  characterizes  the  disin- 
tegration of  the  dead  body. 

This  is  not  the  only  cause  of  disintegration,  since  the 
dead  body  becomes  also  the  prey  of  the  destructive  action 
of  microorganisms  from  the  air  and  in  the  intestine. 
During  life  these  same  microorganisms  are  powerless  in 
their  attack  on  the  cells  protected  by  a  normal  membrane, 
but  after  death  this  membrane  is  destroyed  and  the  action 
of  microorganisms  can  superimpose  itself  on  that  of  di- 
gestion. It  is  also  probable  that  the  normal  secretions  of 
the  mucous  membranes  during  life  have  a  protective 
effect. 

Death,  then,  in  a  human  being  means  the  permanent 


DEATH  AND  THE  DURATION  OF  LIFE      87 

cessation  of  respiration.     We  know  that  this  result  can 
be  brought  about  by  mechanical  violence,  by  poison,  and 
by  disease,  and,  since  nobody  can  escape  all  these  agencies, 
doubts  have  arisen  whether  we  do  not  all  die  from  injury 
or  disease,  and  whether  such  a  thing  as  natural  death 
really  exists.     If  there  were  no  natural  death  it  should 
be  possible  to  prolong  life  indefinitely  if  a  complete  pro- 
tection against  disease  and  accidents  could  be  secured.    It 
is  impossible  to  make  such  an  experiment  in  a  human 
being,  since  our  intestine  and  our  respiratory  tract  can 
not  be  kept  free  from  microorganisms.    The  problem  has, 
however,   been   solved    for  certain  insects.     A   Russian 
author,  Bogdanow,  invented  a  method  of  obtaining  the 
common  house-fly  free  from  all  microorganisms,  by  put- 
ting the  newly  laid  eggs  for  a  number  of  minutes  into  a 
solution  of  bichloride  of  mercury  of  sufficient  concentra- 
tion.   Most  eggs  were  killed  in  the  process,  but  some  sur- 
vived and  these  were  free  from  microorganisms  at  their 
surface.     By  keeping  the  eggs  on  sterilized  meat  and  in 
sterile  flasks,  the  maggots  leaving  the  egg  could  find  their 
food  and  develop  into  flies.    A  French  author,  Guyenot, 
continuing  the  experiments  on  the   fruit  fly,  raised  80 
successive   aseptic   generations,    and    Northrop   and    the 
writer  have  raised  thus  far  87  aseptic  successive  genera- 
tions of  the  fruit  fly  on  aseptic  yeast.     In  these  experi- 
ments all  possibility  of  infection,  all  chances  of  accidental 
or  violent  death  were  excluded.    To  make  sure  that  these 
flies  are  absolutely  free  from  microorganisms,  their  dead 
bodies  are  transferred  to  culture  media  such  as  are  used 
for  the  growth  of  bacteria.    If  a  common  fruit  fly  is  put 
on  such  a  culture  medium,  in  24  hours  a  rapid  growth  of 
microorganisms  develops,  while  the  culture  medium  on 
which  our  aseptic  flies  were  put  remained  free  from  all 
growth  for  years  (or  rather  permanently).    Aseptic  fruit 
flies,  free  from  infectious  disease  and  supplied  with  proper 
food  will,   therefore,  not  escape  death.     These  experi- 
ments, then,  indicate  that  higher  organisms  must  die  from 


88  CONTEMPORARY  SCIENCE 

internal  causes  even  if  all  chance  of  infection  and  all  acci- 
dents are  excluded. 

II 

These  aseptic  flies  served  as  a  means  for  testing  an 
idea  concerning  the  duration  of  life  which  presented  it- 
self, namely,  that  old  age  and  natural  death  are  due  either 
to  the  gradual  production  in  the  body  of  a  sufficient  quan- 
tity of  harmful  or  toxic  substances,  or  to  the  gradual  de- 
struction of  substances  in  the  body  required  to  keep  it  in 
youthful  vigor,  or  to  both.  On  this  basis  the  natural 
duration  of  life  would  be  in  reality  the  time  required  to 
complete  a  chemical  reaction  or  a  series  of  chemical  re- 
actions, resulting  in  the  production  of  toxic  compounds  in 
a  quantity  sufficient  to  kill,  or  resulting  in  the  destruction 
of  necessary  compounds.  Metchnikoif  had  called  atten- 
tion to  the  fact  that  toxic  substances  were  formed  in  the 
intestine  under  the  influence  of  microorganisms.  The  in- 
testine of  aseptic  flies  is  free  from  microorganisms,  so 
that  the  source  for  the  shortening  of  life  pointed  out  by 
Metchnikoff  need  not  be  considered  in  this  case.  The 
toxic  substances  formed  might  be  substances  formed  in 
one  or  several  organs  of  the  body  during  their  normal  ac- 
tivity. Modern  physical  chemistry  furnishes  the  means  of 
testing  such  an  idea.  The  period  of  time  required  to 
complete  a  chemical  reaction  diminishes  rapidly  when  the 
temperature  is  raised  and  increases  rapidly  when  the  tem- 
perature is  lowered.  Experiments  show  that  the  time  re- 
quired for  the  completion  of  a  chemical  reaction  is  doubled 
or  trebled  when  the  temperature  is  lowered  by  io°  centi- 
grade. This  influence  of  temperature  upon  the  rate  of 
processes  of  nature  seems  to  be  typical  for  chemical  re- 
actions. If,  therefore,  the  duration  of  life  is  the  time 
required  for  the  completion  of  certain  chemical  reactions 
in  the  body  we  might  expect  that  the  duration  of  life  will 
be  doubled  or  trebled  when  we  lower  the  temperature  ten 


DEATH  AND  THE  DURATION  OF  LIFE      89 

degrees  centigrade.  Such  experiments  can  be  carried  out 
only  in  organisms  where  accidental  death  by  infection  is 
excluded  and  our  aseptic  fruit  flies  satisfied  this  condi- 
tion. These  experiments  were  made  by  Dr.  Northrop 
and  the  writer,  and  consisted  in  putting  a  number  of 
newly  laid  eggs  of  aseptic  flies  on  an  abundance  of  steril- 
ized yeast  (which  is  their  natural  food)  in  a  flask  plugged 
with  cotton.  These  flasks  were  put  into  incubators  the 
temperature  of  which  was  kept  constant  within  0.2  of  a 
degree  centigrade.  The  temperatures  selected  for  the 
purpose  were  10,  15,  20,  25,  27.5,  and  30°  C.  It  is  not 
possible  to  go  into  the  numerous  precautions  which  it  was 
necessary  to  take  and  the  many  technical  difficulties  in- 
volved in  this  investigation.  The  result  of  a  large  number 
of  experiments  was  that  the  duration  of  life  of  such  asep- 
tic flies  was  a  definite  one  for  each  temperature,  which 
means  that  all  the  flies  died  at  practically  the  same  age 
when  kept  at  the  same  temperature.  Thus,  for  instance, 
the  total  average  duration  of  hfe  of  such  flies  was  21.15 
days  at  30°  C.  The  overwhelming  majority  died  at  that 
age,  but  a  few  died  a  little  earlier  and  a  few  a  little  later. 
When  the  number  of  flies  of  a  culture  which  die  on  suc- 
cessive days  is  plotted  in  terms  of  percentage  of  the 
original  number  of  flies,  we  get  that  curve  of  death  rates 
usually  given  in  life  insurance  statistics.  But  this  curve 
is  very  steep  in  our  case  owing  to  the  fact  that  the  ma- 
jority of  flies  die  at  about  the  same  time  for  a  given  con- 
stant temperature.  The  following  table  gives  the  average 
duration  of  life  of  the  fly  in  days  for  different  tempera- 
tures. 

TABLE  I 


Temperature, 

Average  Duration  of  Life  of  th 

°C. 

Fly  from  Egg  to  Death,  Days 

30 

21.15 

25 

38.5 

20 

54.3 

15 

123.3 

10 

177.5  -h  X 

90  CONTEMPORARY  SCIENCE 

This  table  shows  that  the  influence  of  temperature  on 
the  duration  of  Hfe  of  the  fly  is  the  same  as  the  influence 
of  temperature  on  the  velocity  of  a  chemical  reaction,  in- 
asmuch as  a  lowering  of  the  temperature  by  ten  degrees 
results  in  an  increase  in  the  duration  of  life  by  two  or 
three  hundred  per  cent.,  and  the  same  figure  would  be 
obtained  if  we  investigated  the  effect  of  temperature  upon 
the  time  required  to  complete  a  chemical  reaction.  At 
30°  C.  the  flies  live  on  an  average  21.15  days  and  at 
20°  C.  they  will  live  on  an  average  54.3  days  or  a  little 
over  twice  as  long.  At  25°  they  live  38.5  days  and  at 
15°  C.  123.9  days  or  about  three  times  as  long.  The  fruit 
fly  is  a  tropical  organism  and  30°  C.  is  not  far  from  the 
optimal  temperature.  By  lowering  their  temperature 
twenty  degrees  we  prolong  the  duration  of  their  life  by 
nine  hundred  per  cent.  We  cannot  lower  the  temperature 
below  10°  since  the  flies  suffer  in  the  chrysalid  stage  when 
the  temperature  becomes  10°  or  less.  While  these  are 
thus  far  the  only  experiments  on  the  duration  of  life  of 
higher  organisms  carried  out  with  the  necessary  scientific 
precaution,  there  are  many  casual  observations  mentioned 
in  the  literature  which  suggest  that  lowering  the  tempera- 
ture prolongs  the  duration  of  life  of  lower  animals  in 
general. 

The  body  temperature  of  a  normal  human  being  is 
constant,  namely  about  37.5°  C.  and  this  temperature  re- 
mains the  same  in  the  tropics  and  in  the  arctic  regions. 
Human  beings  and  most  mammals  differ  in  this  respect 
from  insects  whose  temperature  is  as  a  rule  practically 
that  of  their  surroundings.  If  it  were  possible  to  reduce 
the  temperature  of  human  beings  and  if  the  influence  of 
temperature  on  the  duration  of  life  were  the  same  as 
that  in  the  fruit  fly,  a  reduction  of  our  temperature  from 
37.5  to  about  16°  would  lengthen  the  duration  of  our  life 
to  that  of  Methusaleh ;  and  if  we  could  keep  the  tempera- 
ture of  our  blood  permanently  at  7.5°  C,  our  average  life 
would    (on  the  same  assumption)    be  lengthened   from 


DEATH  AND  THE  DURATION  OF  LIFE      91 

three  score  and  ten  to  about  2y  times  that  length,  %,€.,  to 
about  nineteen  hundred  years.  Unfortunately  our  body 
does  not  tolerate  any  considerable  lowering  of  its  tem- 
perature and  if  it  did,  life  at  so  low  a  temperature  would 
probably  become  very  monotonous  and  uninteresting  since 
in  all  probability  sensations  of  pleasure  as  well  as  pain, 
of  joy  and  of  sadness,  would  be  at  a  very  low  level. 

The  experiments  on  aseptic  flies  therefore  lend  support 
to  the  idea  that  the  duration  of  our  life  is  the  time  re- 
quired for  the  completion  of  a  chemical  reaction  or  a 
series  of  chemical  reactions.  If  these  reactions  consist 
in  the  gradual  accumulation  of  harmful  products  in  our 
body,  or  in  the  gradual  destruction  of  substances  required 
for  a  youthful  condition,  we  understand  why  senile  decay 
and  death  are  the  natural  result  of  life. 

Ill 

Unicellular  organisms,  like  bacteria,  algse  or  infusorians, 
seem  to  be  immortal.  They  reach  a  certain  size,  divide 
into  two,  each  half  growing  again  to  full  size  and  divid- 
ing again,  and  so  on.  In  this  case  we  may  say  that  it  is 
practically  the  same  individual  which  continues  to  live  in 
the  successive  generations.  Small  pieces  of  a  cancerous 
tumor  can  be  transplanted  successfully  to  other  individ- 
uals and  these  pieces  grow  again  to  a  large  size.  This 
process  can  also  be  repeated  indefinitely,  and  it  is  the 
same  cancer  cell  which  continues  to  live  in  these  succes- 
sive transplantations,  as  it  is  the  same  bacterium  which 
continues  to  live  in  successive  generations.  In  this  way 
it  has  been  shown  that  cancers  in  mice  may  outlive  many 
times  the  natural  life  of  a  mouse,  in  fact  they  seem  to 
live  indefinitely.  Cancer  cells  may  therefore  be  called 
immortal  as  was  pointed  out  by  Leo  Loeb  many  years 
ago. 

It  seems  that  this  is  true  also  for  certain  normal  cells 
like  connective  tissue  cells.  Carrel  has  isolated  connec- 
tive tissue  cells  from  the  heart  of  a  chick  embryo  and 


92  CONTEMPORARY  SCIENCE 

cultures  of  these  cells  living  on  the  extracts  from  chick 
embryos  have  been  kept  alive  now  for  seven  years. 

All  this  points  to  the  idea  that  death  is  not  inherent  in 
the  individual  cell,  but  is  only  the  fate  of  more  compli- 
cated organisms  in  which  different  types  of  cells  or  tissues 
are  dependent  upon  each  other.  In  this  case  it  seems  to 
happen  that  one  or  certain  types  of  cells  produce  a  sub- 
stance or  substances  which  gradually  become  harmful 
to  a  vital  organ  like  the  respiratory  center  of  the  medulla, 
J  or  that  certain  tissues  consume  or  destroy  substances 
which  are  needed  for  the  life  of  some  vital  organ.  The 
mischief  of  death  of  complex  organisms  may  then  be 
traced  to  the  activity  of  a  black  sheep  in  the  society  of 
tissues  and  organs  which  constitute  a  complicated  multi- 
cellular organism. 

IV 

While  in  human  beings  there  is  no  sharp  limit  between 
youth  and  maturity,  in  many  insects  and  amphibians  this 
limit  is  marked  by  a  sudden  metamorphosis  in  the  shape 
of  their  body.  The  frog  hatches  from  the  egg  as  a  tad- 
pole without  legs  and  with  a  long  tail.  After  a  certain 
length  of  time  legs  begin  to  grow,  the  tail  disappears,  the 
form  of  the  head  and  mouth  change,  the  skin  looks  dif- 
ferent, and  the  tadpole  is  transformed  into  a  frog.  It 
is  possible  that  some  of  the  changes  underlying  metamor- 
phosis are  due  to  changes  in  the  circulation  of  the  blood. 
Gudernatsch  made  the  remarkable  discovery  that  this 
metamorphosis,  which  in  our  climate  usually  occurs  dur- 
ing the  third  or  fourth  month  of  the  life  of  the  tadpole, 
can  be  brought  about  at  will  even  in  the  youngest  tad- 
poles, by  feeding  them  with  thyroid  gland,  no  matter  from 
which  animal.  By  feeding  very  young  tadpoles  with  this 
substance,  frogs  not  larger  than  a  fly  could  be  produced. 
Allen  added  the  observation  that  if  a  young  tadpole  is 
deprived  of  its  thyroid  gland,  it  is  unable  ever  to  become 
a  frog;  and  that  it  remains  a  tadpole  which  can  reach, 


DEATH  AND  THE  DURATION  OF  LIFE      93 

however,  a  long  life  and  continue  to  grow  beyond  the 
usual  size  of  the  tadpole.  When,  however,  such  super- 
annuated tadpoles  are  fed  with  thyroid  they  promptly 
undergo  metamorphosis.  These  observations  cleared  up 
an  old  biological  puzzle.  Salamanders  also  go  through  a 
metamorphosis  which  is,  however,  less  striking  than  that 
of  the  tadpole  of  a  frog.  In  the  salamander  the  metamor- 
phosis consists  chiefly  in  the  throwing  off  of  the  gills,  and 
in  changes  in  skin  and  tail.  In  Mexico  a  salamander  oc- 
curs which  through  its  whole  life  maintains  its  tadpole 
form,  namely  the  axolotl.  Attempts  to  induce  the  axolotl 
to  metamorphose  failed  until  after  Gudernatsch's  discov- 
ery an  investigator  fed  the  axolotl  thyroid  gland,  and  this 
brought  about  metamorphosis.  The  thyroid  gland  stores 
the  traces  of  iodine  taken  up  in  our  food  and  it  seemed 
possible  that  the  iodine  contained  in  the  thyroid  was  the 
active  principle  causing  metamorphosis  in  tadpoles.  This 
was  confirmed  by  Swingle  who  succeeded  in  inducing 
metamorphosis  in  tadpoles  by  feeding  them  with  traces  of 
inorganic  iodine.  According  to  our  present  knowledge, 
the  duration  of  the  tadpole  stage  seems  to  be  the  time  re- 
quired to  store  the  necessary  amount  of  certain  com- 
pounds, one  of  which  contains  iodine. 

Insects,  like  the  fruit  fly,  hatch  from  the  egg  as  mag- 
gots which  grow  at  the  expense  of  the  food  they  take  up 
and  which,  at  a  certain  age,  metamorphose  into  a  chrysa- 
lid;  and  from  thischrysalid  at  a  given  time  will  rise  the 
winged  fly.  Feeding  of  thyroid  to  the  maggots  of  the 
fruit  fly  will  not  accelerate  their  metamorphosis,  and  we 
can  not  tell  whether  in  this  case  metamorphosis  is  due  to 
the  accumulation  or  formation  of  a  definite  compound  in 
the  body,  though  this  may  well  be  the  case.  The  idea 
presented  itself  whether  the  duration  of  the  larval  or 
maggot  stage  was  not  also  determined  by  the  temperature 
(provided  the  food  supply  was  adequate).  We  meas- 
ured, therefore,  the  influence  of  temperature  upon  the 
duration  of  the  larval  state  in  aseptic  fruit  flies — i.e.,  from 


94  CONTEMPORARY  SCIENCE 

the  time  the  egg  was  laid  until  the  maggot  was  trans- 
formed into  a  chrysalid.  The  influence  was  practically 
identical  with  that  of  temperature  on  the  total  duration 
of  life.  Thus  the  larval  period  lasted  5.8  days  at  25°  C. 
and  17.8  days  at  15°  C,  a  ratio  of  about  i :  3.  The  total 
duration  of  life  of  aseptic  flies  is  38.5  days  at  25°  and 
123.9  days  at  15°  C,  also  a  ratio  of  about  i :  3.  We  are, 
therefore,  justified  in  making  the  statement  that  the  in- 
fluence of  temperature  upon  the  duration  of  the  larval 
period  or  the  youth  of  aseptic  flies  is  practically  identical 
with  the  influence  of  temperature  on  the  total  duration  of 
life. 

Experiments  by  Uhlenhuth  on  the  influence  of  tempera- 
ture on  metamorphosis  in  salamanders  have  shown  that 
it  is  similar  to  that  observed  in  flies.  Salamanders  kept 
at  25°  metamorphosed  when  they  were  11  weeks  old, 
while  salamanders  kept  at  15°,  under  otherwise  identical 
conditions,  metamorphosed  when  they  were  22  weeks  old. 
All  these  data  suggest  the  possibility  that  the  duration  of 
life  and  the  duration  of  the  larval  period  or  of  youth  are 
in  reality  times  required  for  the  completion  of  definite 
chemical  reactions.  The  cessation  of  respiration  leading 
to  the  termination  of  life  and  the  alterations  in  circula- 
tion leading  to  metamorphosis  or  termination  of  youth 
are  critical  points ;  and  it  seems  possible  that  these  points 
are  reached  when  a  certain  toxic  substance  is  formed  in 
adequate  quantity  in  the  body,  or  when  a  necessary  sub- 
stance is  destroyed  or  sufliciently  diminished  in  quantity, 
or  when  both  conditions  are  fulfilled. 

We  can  prolong  or  shorten  the  period  of  youth  in 
amphibians  not  only  by  modifying  the  temperature  but 
by  withdrawing  or  offering  the  specific  substance  which 
causes  metamorphosis,  namely  iodine  or  thyroid  material. 
There  is  no  end  to  the  substances  capable  of  hastening 
death.  Shall  we  ever  find  a  substancfe  which  will  pro- 
long the  duration  of  life?  At  present  we  can  neither 
deny  nor  affirm  the  possibility. 


THE  PHYSIOLOGY  OF  THE  AVIATOR 

(Address  before  the  Harvey  Society,  New  York 
City,  March  2.2,  1919) 

BY 

Yandell  Henderson 
Professor  of  Physiology,    Yale   University 

Doubtless  you  have  all  read  the  delightful  historical 
accounts  by  the  late  Admiral  Mahan  of  the  great  naval 
battles  of  the  eighteenth  century,  when  France  and  Eng- 
land struggled  for  the  mastery  of  the  sea.  You  will  re- 
call the  stress  laid  on  the  weather  gauge,  or  windward 
position.  If  the  wind  blew  from  the  eastward,  as  does 
the  "northeast  trade"  among  the  Caribbean  Islands  where 
a  great  part  of  the  struggle  occurred,  whichever  admiral 
was  able  so  to  maneuver  as  to  be  to  the  east  of  his  enemy 
obtained  a  great,  and  often  a  decisive,  advantage.  He 
could  choose  the  time  and  mode  of  attack,  while  his  an- 
tagonist was  compelled  to  remain  on  the  defensive,  unable 
either  to  force  the  fighting  or  to  escape  it. 

In  modern  naval  warfare  the  position  of  the  sun  in  re- 
lation to  the  enemy's  fleet  affects  the  accuracy  of  aim. 
The  speed  of  the  ships  is  of  importance  equalling  that  of 
their  gunfire.  But  there  is  no  element  of  position  which 
quite  corresponds  to  that  of  the  weather  gauge  for  a 
fleet  under  sail. 

In  the  battles  of  the  ships  of  the  air,  however,  there  is 

95 


96  CONTEMPORARY  SCIENCE 

again  a  condition  which  corresponds  quite  closely  to  the 
tactical  advantage  of  maneuvering  between  the  wind  and 
the  enemy.  In  this  case  it  is  not  a  direction  in  the  plane 
of  the  horizon,  except  so  far  as  light  is  important ;  but  it 
is  the  direction  at  right  angles,  vertical  to  this  plane.  It 
is  the  upper  position — the  advantage  obtained  by  him  who 
can  climb  above  his  enemy,  and,  choosing  the  moment 
of  attack,  can  swoop  down  upon  him  from  above. 

With  this  as  one  of  the  fundamental  conditions  of 
aerial  warfare,  it  was  inevitable  that  in  the  development 
of  the  battle  plane  there  should  be  the  utmost  effort  to 
produce  machines  of  continually  greater  speed  and,  its 
correlative,  climbing  power.  Likewise  in  the  air,  the 
greatest  practicable  altitude  has  meant  for  the  flying  man 
at  once  an  advantage  over  his  enemy  and  a  reduction  of 
his  own  chance  of  being  hit  by  anti-aircraft  fire  from  the 
enemy's  guns  on  the  ground. 

Accordingly,  from  the  comparatively  low  altitude  at 
which  the  aerial  fighting  of  the  first  year  of  the  war 
usually  occurred,  the  struggle  rose,  as  more  and  more 
powerful  airplanes  were  constructed  by  both  sides,  until 
at  the  end  of  the  war  it  was  quite  common  for  battle 
planes  to  ascend  to  altitudes  of  15,000  to  18,000  feet — 
three  miles  up,  higher  than  the  summits  of  the  Rocky 
Mountains  or  the  Alps. 

Along  with  this  development  there  occurred  with  in- 
creasing frequency  among  the  aviators  a  condition  of  so- 
called  "air-staleness."  It  is  a  condition  closely  similar  to, 
perhaps  identical  with,  the  "over-training"  or  staleness, 
the  physical  and  nervous  impairment  of  athletes  in  a  foot- 
ball team  or  college  crew.  In  the  last  year  of  the  war  this 
condition  had  become  so  common  that,  as  reported  to  us 
by  some  observers,  the  majority  of  the  more  experienced 
aviators  in  the  British  service  were  incapacitated  to  as- 
cend to  the  necessary  altitude,  and  many  could  no  longer 
fly  at  all.  It  was  to  make  good  this  most  serious  military 
deficiency  that  the  enlistment  and  training  of  aviators 


THE  PHYSIOLOGY   OF   THE  AVIATOR    97 

were  undertaken  by  the  American  Air  Service  on  the 
enormous  scale  that  they  were.  It  was  for  the  purpose  of 
testing  our  airmen  initially,  and  of  keeping  tab  on  their 
physical  condition  thereafter,  that  the  work  at  the  Mineola 
laboratory,  of  which  probably  you  have  heard,  was  under- 
taken. 

It  is  work  which  lies  in  a  field  of  physiology  in  which 
before  the  war  not  half  a  dozen  men  in  America,  and  not 
many  more  in  Europe,  were  interested,  and  for  them  it 
was  a  field  of  what  is  called  "pure"  science.  To-day  it 
promises  contributions  of  practical  value  not  only  to 
aviation,  but  to  problems  in  medicine,  climatology,  ath- 
letics and  hygiene. 

We  will  turn  then  to  the  problem  of  the  aviator  and 
the  methods  of  human  engineering  which  have  been  de- 
veloped for  its  solution.  But  first,  it  will  be  advisable  to 
review  briefly  what  is  known  concerning  the  immediate 
effects  of  low  baronietric  pressure  and  the  functional  re- 
adjustments involved  in  acclimatization  to  elevated  re- 
gions; that  is,  life  at  great  altitudes. 

Paul  Bert,^  the  brilliant  French  physiologist,  was  the 
first  to  demonstrate,  in  1878,  that  the  effects  of  lowered 
barometric  pressure  or  altitude  are  wholly  dependent  on 
the  decreased  pressure  of  oxygen.  He  carried  out  experi- 
ments upon  men  and  animals  both  with  artificial  gas  mix- 
tures and  reduced  barometric  pressure  in  a  steel  chamber. 

He  showed  that  in  pure  oxygen  at  21  per  cent,  of  at- 
mospheric pressure  life  goes  on  in  practically  the  same 
manner  as  in  air,  which  contains  21  per  cent,  of  oxygen, 
at  the  ordinary  pressure.  So  also  the  breathing  of  an 
artificial  gas  mixture  containing  only  10.5  per  cent,  of 
oxygen  has  the  same  untoward  effects  at  sea  level  that 
breathing  pure  air  has  at  an  altitude  of  about  20,000  feet, 
where  the  barometer  is  reduced  by  one  half. 

These  considerations  are  fundamental  for  the  diiferen- 
tiation  of  the  disorders  induced  by  rarefied  air — so-called 

1  Paul  Bert,  La  Pression  Barometrique,  Paris,  1878. 


98  CONTEMPORARY  SCIENCE 

mountain  sickness — from  the  conditions  resulting  from 
work  in  compressed  air — so-called  caisson  disease.  It  is 
clear  that  it  is  from  the  former,  and  not  at  all  from  the 
latter,  that  aviators  suffer;  but,  as  the  two  disorders  are 
sometimes  confused,  a  few  words  regarding  the  latter 
are  in  place  here. 

Caisson  disease — ^known  also  as  the  "bends,"  "diver's 
palsy/'  and  by  other  names — depends  upon  the  fact  that, 
under  the  high  pressure  necessary  for  diving,  tunneling, 
and  other  work  below  water,  the  nitrogen  of  the  air  dis- 
solves in  the  blood  and  in  the  other  fluids  and  tissues  of 
the  body  in  amounts  proportional  to  the  pressure.  This 
in  itself  does  no  harm,  and  has  in  fact  no  effect  upon  the 
body,  until  the  subject  comes  out  of  the  pressure  lock 
or  caisson,  or  rises  from  the  depth  of  the  sea  where  he  has 
been  working.  Then  the  nitrogen  which  has  been  dis- 
solved begins  to  diffuse  out  of  the  body.  This  also  does 
no  harm  and  has  no  effect  unless  the  pressure  under 
which  the  man  has  been  working  is  so  high,  and  the  low- 
ering of  the  external  pressure  is  so  rapid,  that  the  dis- 
solved nitrogen  separates  in  the  form  of  bubbles.  Such 
bubbles  may  form  in  the  blood,  in  the  synovial  fluid  of 
the  joints,  and  even  in  the  brain.  They  induce  intense 
pain,  and  even  paralysis  and  death.  In  order  that  bub- 
bles may  be  formed  it  is  essential,  however,  that  the 
pressure  with  which  the  tissues  are  in  equilibrium  should 
have  been  lowered  considerably  more  than  half  its  abso- 
lute amount  in  a  few  seconds. 

In  the  present  state  of  the  art  of  flying  it  is  scarcely 
possible  for  an  aviator  to  rise  to  a  height  of  more  than 
20,000  feet,  where  the  barometer  would  be  less  than  half 
of  that  at  sea  level,  in  a  period  sufliciently  short  to  allow 
bubbles  of  nitrogen  to  form  in  this  way.  The  disorders 
from  which  aviators  suffer  are,  therefore,  of  a  different 
class  from  those  to  which  workers  in  compressed  air  are 
exposed. 

When  the  study  of  the  effects  of  lowered  barometric 


THE  PHYSIOLOGY  OF  THE  AVIATOR    99 

pressure  was  begun,  it  was  supposed  that  t*he  circulation 
might  be  primarily  disturbed.  The  blood  in  the  arteries 
of  a  healthy  man  is  under  such  a  pressure  that,  if  a  glass 
tube  were  inserted  vertically  into  one  of  the  arteries  of 
his  neck,  and  the  blood  were  allowed  to  flow  up  the  tube,, 
the  column  of  blood  would  come  to  rest  at  a  height  of  4 
or  5  feet  above  his  heart,  corresponding  to  pressures  of 
120  to  150  mm.  mercury.  Knowing  that  the  air  pressure 
is  reduced  at  great  altitudes,  some  of  the  earlier  writers 
made  the  mistake  of  supposing  that  such  a  column  of 
blood  would  rise  higher,  and  the  blood  vessels  would  be 
under  a  greater  strain,  and  more  likely  to  burst  therefore, 
at  a  great  altitude  than  at  sea  level.  That  which  they 
looked  for  they  found.  One  writer  has  left  a  lurid  de- 
scription of  how,  while  crossing  a  pass  in  the  Andes,  he 
got  off  his  mule  and  walked  for  a  time  to  rest  the  animal. 
On  the  least  exertion  his  breathing  became  oppressed,, 
"his  eyes  bulged  and  his  lips  burst."  The  odd  part  of 
this  is  that  in  reality  the  blood  vessels  are  under  no 
greater  strain  at  a  high  altitude  than  at  sea  level.  When 
the  air  pressure  upon  the  exterior  of  the  body  and  in  the 
lungs  is  reduced,  a  part  of  the  gas — at  least  the  nitrogen 
dissolved  in  the  blood — rapidly  diffuses  out  through  the 
lungs,  so  that  the  gas  pressure  within  and  without  the 
blood  vessels  are  again  equal  just  as  at  sea  level.  The 
idea  is  still  prevalent  that  hemorrhages  occur  under  low 
barometric  pressures.  However,  among  thousands  of 
people  whom  I  had  an  opportunity  to  observe  on  Pike's 
Peak  during  a  five-weeks'  stay  at  the  summit,  I  saw  not 
a  single  nose  bleed,  except  one  which  was  caused  by  the 
forcible  application  of  a  hard  object  to  the  organ  in 
question. 

The  only  direct  effects  of  changes  of  pressure  are  those 
which  are  felt  in  the  ears,  and  occasionally  in  the  sinuses 
connected  with  the  nose.  The  ear  drums  are  connected 
with  the  throat  and  contain  air  at  the  prevailing  pres- 
sure.    If  the  pressure  is  lowered  this  air  expands,  and 


100  CONTEMPORARY  SCIENCE 

forces  its  way  out  through  the  Eustachian  tubes  into  the 
throat.  If  the  outside  pressure  is  increased,  it  sometimes 
happens,  particularly  when  the  subject  has  a  cold  and 
the  Eustachian  tubes  are  inflamed,  that  air  does  not  pass 
readily  into  the  middle  ear.  Accordingly  the  tympanic 
membranes  are  forced  inward  by  the  pressure;  and  this 
may  cause  acute  pain.  Workers  in  compressed  air  are 
accustomed,  while  going  "into  the  air,"  i.e.,  into  pressure, 
to  hold  their  noses  and  blow  at  frequent  intervals  as  a 
means  for  expanding  the  ear  drums.  Aviators  even  dur- 
ing very  rapid  descents  are  generally  relieved  by  merely 
swallowing. 

To  sum  up  all  that  has  been  said  thus  far,  the  influence 
of  low  barometric  pressure  is  not  mechanical  but  chemi- 
cal. Life  is  often  compared  to  a  flame ;  but  there  are 
marked  differences,  depending  upon  the  peculiar  affinity 
of  the  blood  for  oxygen.  A  man  may  breathe  quite  com- 
fortably in  an  atmosphere  in  which  a  candle  is  extin- 
guished. The  candle  will  burn  with  only  slightly  dimin- 
ished brightness  at  an  altitude  at  which  a  man  collapses. 
The  candle  is  affected  by  the  proportions  of  oxygen  and 
nitrogen.  The  living  organism  depends  solely  upon  the 
absolute  amount  of  oxygen — its  so-called  partial  pres- 
sure. 

Unlike  the  flame,  a  man  may  become  acclimatized  to 
a  change  of  atmosphere  in  the  course  of  a  few  days  or 
weeks.  He  is  thus  adjusted  to  the  mean  barometric  pres- 
sure under  which  he  lives.  Every  healthy  person  is  so 
adjusted.  New  Yorkers  to  a  mean  barometric  pressure 
of  760  mm.  no  less  than  the  inhabitants  of  Denver  or 
Cripple  Creek  to  their  altitudes.  Even  your  tall  build- 
ings could  probably  be  shown  to  exert  a  slight  climatic 
effect  upon  the  tenants  of  the  upper  stories.  The  study 
of  the  processes  involved  in  such  acclimatization  affords 
lis  one  of  the  most  promising  means  of  analyzing  some 
of  the  fundamental  problems  of  Hfe.  In  fact,  is  not  the 
gaseous  interchange  of  protoplasm,  the  carbon  and  oxygen 


THE  PHYSIOLOGY  OF  THE  AVIATOR     loi 

metabolism  of  the  cell,  the  central  fact  of  life?  Is  not 
the  mode  of  regulation  of  the  interior  environment  of 
the  body — the  constants  of  the  "humors" — the  prime  prob- 
lem of  the  "vegetative"  side  of  physiology? 

Among  the  ill  effects  of  lack  of  oxygen  we  may  distin- 
guish three  more  or  less  distinct  conditions.  They  are 
comparable,  in  terms  of  more  common  disorders,  to  acute 
disease  in  contrast  with  chronic  conditions  of  various  de- 
grees. Thus  any  one  suddenly  exposed  to  acute  depriva- 
tion of  oxygen,  as  is  the  balloonist  or  the  aviator  in  very 
lofty  ascents,  shows  one  set  of  symptoms.  If  the  ex- 
posure is  less  acute,  as  in  the  case  of  one  taking  up  resi- 
dence on  a  high  mountain,  the  effects  develop  gradually ;; 
he  passes  through  the  stages  of  mountain  sickness,  a  con- 
dition much  like  sea  sickness,  to  a  state  of  acclimatization 
and  renewed  health.  If,  however,  the  ascent  or  the  flight 
is  for  only  two  or  three  hours,  a  period  too  short  for  any 
degree  of  acclimatization  to  develop,  and  this  strain  on 
the  oxygen-needing  organs  is  repeated  daily,  as  is  the 
case  with  the  aviator  of  the  upper  air,  the  condition  of 
"air  staleness"  is  likely  sooner  or  later  to  result.  It  is. 
the  effect  of  repeated  slight  oxygen  deficiency  on  an  in- 
dividual who  does  not  become  acclimatized.  It  is,  I  be- 
lieve, closely  related  to  those  effects  of  repeated  over- 
exertion and  oxygen  shortage  which  appear  in  the  over- 
trained athlete. 

The  classic  description  of  collapse  from  oxygen  de- 
ficiency is  that  written  by  Tissandier,^  the  sole  survivor 
of  a  fatal  balloon  ascent  in  1875. 

I  now  come  to  the  fateful  moments  when  we  were 
overcome  by  the  terrible  action  of  reduced  pressure. 
At  7,000  meters  (Bar.  320  mm.)  we  were  all  below 
in  the  car.  .  .  .  Torpor  had  seized  me.  My  hands 
were  cold  and  I  wished  to  put  on  my  fur  gloves ;  but 
without  my  being  aware  of  it,  the  action  of  taking 
2  Quoted  from  Paul  Bert,  op.  cit,  p.  1061. 


102  CONTEMPORARY  SCIENCE 

them  from  my  pocket  required  an  effort  which  I  was 
unable  to  make.  At  this  height  I  wrote,  nevertheless, 
in  my  notebook  almost  mechanically,  and  reproduce 
literally  the  following  words,  though  I  have  no  very 
clear  recollection  of  writing  them.  They  are  written 
very  illegibly  by  a  hand  rendered  very  shaky  by  the 
cold:  My  hands  are  frozen.  I  am  well.  We  are 
well.  Haze  on  the  horizon,  with  small  rounded  cir- 
rus. We  are  raising.  Croce  is  panting.  We  breathe 
oxygen.  Sivel  shuts  his  eyes.  Croce  also  shuts  his 
eyes.  I  empty  aspirator.  1.20  p.m., — 11°,  Bar.  320. 
Sivel  is  dozing.  1.25 — 11°,  Bar.  =  300.  Sivel  throws 
tallast.  Sivel  throws  ballast.  (The  last  words  are 
scarcely  legible.)  ...  I  had  taken  care  to  keep  ab- 
solutely still,  without  suspecting  that  I  had  already 
perhaps  lost  the  use  of  my  limbs.  At  about  7,500 
ineters  (Bar.  300  mm.)  the  condition  of  torpor  which 
comes  over  one  is  extraordinary.  Body  and  mind 
become  feebler  little  by  little,  gradually  and  insen- 
sibly. There  is  no  suffering.  On  the  contrary  one 
feels  an  inward  joy.  There  is  no  thought  of  the 
dangerous  position ;  one  rises  and  is  glad  to  be  rising. 
The  vertigo  of  high  altitudes  is  not  an  empty  word; 
tut  so  far  as  I  can  judge  from  my  own  impressions 
this  vertigo  appears  at  the  last  moment,  and  immedi- 
ately precedes  extinction,  sudden,  unexpected  and  ir- 
resistible. ...  I  soon  felt  myself  so  weak  that  I 
could  not  even  turn  my  head  to  look  at  my  compan- 
ions. I  wished  to  take  hold  of  the  oxygen  tube,  but 
found  that  I  could  not  move  my  arms.  My  mind  was 
still  clear,  however,  and  I  watched  the  aneroid  with 
my  eyes  fixed  on  the  needle,  which  soon  pointed  to 
290  mm.  and  then  to  280.  I  wished  to  call  out  that 
we  were  now  at  8,000  meters;  but  my  tongue  was 
paralyzed.  All  at  once  I  shut  my  eyes  and  fell  down 
powerless,  and  lost  all  further  memory.  It  was  about 
L.'^o. 


THE  PHYSIOLOGY  OF  THE  AVIATOR     103 

In  this  ascent  the  balloon  continued  to  rise  until  a  mini- 
mum pressure,  registered  automatically,  of  263  mm.  was 
reached.  When  Tissandier  recovered  consciousness  Sivel 
and  Croce-Spinelli  were  dead.  They  were  all  provided 
with  oxygen,  ready  to  breath;  but  all  were  paralyzed  be- 
fore they  could  raise  the  tubes  to  their  lips.  Tissandier's 
notes  are  characteristic  of  the  mental  condition  when 
oxygen-want  is  becoming  dangerous. 

In  marked  contrast  to  this  condition  is  that  of  men  who, 
gradually  ascending  into  the  mountains,  day  by  day  be- 
come acclimatized  without  realizing  that  any  change  has 
occurred.  The  record  for  the  greatest  altitude  attained 
by  mountaineers  is  held  by  the  Duke  of  Abruzzi  and  his 
party  in  the  Himalayas.  They  reached  an  altitude  of 
24,000  feet,  where  the  atmospheric  pressure  is  only  two- 
fifths  of  that  at  sea  level,  or  practically  the  same  as  that 
at  which  Tissandier's  companions  lost  consciousness.  At 
this  tremendous  altitude  the  Duke  and  his  Swiss  guides 
were  not  only  free  from  discomfort,  but  were  able  to 
perform  the  exertion  of  cutting  steps  in  ice  and  climb- 
ing. Dr.  Filippi,  the  physician  who  accompanied  them, 
in  discussing  this  matter  says  that  the  fact  of  their  im- 
munity admits  of  but  one  interpretation : 

Rarefaction  of  the  air  under  ordinary  conditions 
of  the  high  mountains  to  the  limits  reached  by  man  at 
the  present  day  (307  mm.)  does  no't  produce  moun- 
tain sickness.^ 

In  this  statement,  however,  he  is  certainly  mistaken, 
for  the  observations  of  others  show  conclusively  that  the 
sudden  exposure  of  unacclimatized  men  to  an  altitude 
considerably  less  than  that  reached  by  this  party  would 
either  produce  collapse  like  that  of  Tissandier's  compan- 
ions, or  if  long  continued  would  result  in  mountain  sick- 

3  Quoted  from  Douglas,  Haldane,  Henderson  and  Schneider, 
Physiological  Observations  on  Pikes  Peak,  Phil.  Trans.,  1913,  B. 
203,  p.  310. 


I04  CONTEMPORARY  SCIENCE 

ness.  The  latter  effect  especially  is  one  which  was  the 
subject  of  careful  study  by  an  expedition  of  which  I  was 
a  member,  and  which  during  the  summer  of  191 1  spent 
five  weeks  at  the  summit  of  Pike's  Peak,  Colorado,  alti- 
tude, 14,100  feet,  Bar.  450  mm.  We  were  there  enabled 
to  make  observations  upon  hundreds  of  tourists  who  as- 
cended the  Peak,  and  who  were  acclimatized  at  most  to 
the  altitude  of  Colorado  Springs  or  Manitou  at  the  foot 
of  the  mountain.  We  saw  a  number  of  cases  of  collapse 
— fainting — from  oxygen  deficiency  as  shown  by  the 
striking  cyanosis. 

In  the  majority  of  cases,  however,  tourists  who  spent 
no  more  than  the  regulation  half  hour  at  the  summit  of 
the  Peak,  and  then  descended,  experienced  no  acute  ill 
efifects.  Headache  and  some  degree  of  nausea  were  com- 
mon even  among  these  persons,  however — often  develop- 
ing slowly  for  some  hours  after  their  descent.  On  the 
other  hand,  among  persons  who  remained  over  night, 
and  were  thus  exposed  for  several  hours  to  deficiency  of 
oxygen,  the  classic  symptoms  of  mountain  sickness  oc- 
curred ;  and  few  escaped.  Their  second  day  at  the  summit 
was  marked  usually  by  extreme  discomfort — headache, 
nausea,  vomiting,  dizziness  and  extraordinary  instability 
of  temper — symptoms  which  were  strikingly  exacerbated 
by  even  the  smallest  use  of  alcohol. 

Our  immediate  party  passed  through  these  conditions 
and  after  two  or  three  days,  or  in  one  case  nearly  a  week, 
re-attained  practically  normal  health.  A  definite  func- 
tional readjustment  had  occurred.  To  illustrate  and  em- 
phasize the  nature  of  this  readjustment  I  will  quote  a 
recent  experiment  *  of  my  friend  the  leader  of  the  Pike's 
Peak  expedition.  Dr.  J.  S.  Haldrane. 

He  has  equipped  his  laboratory  at  Oxford  with  a  small 
lead-lined  chamber  in  which  a  man  can  be  hermetically 
closed.  The  carbonic  acid  which  he  exhales  is  continually 
absorbed  by  alkali,  so  that  no  accumulation  occurs,  while 

*  Personal  communication. 


THE  PHYSIOLOGY  OF  THE  AVIATOR     105 

the  oxygen  is  progressively  decreased  by  the  breathing  of 
the  man  himself.  Dr.  Haldane  found  that  after  a  day 
or  two  in  this  chamber  he  had  reduced  the  oxygen  to  an 
extent  comparable  to  Pike's  Peak.  At  the  same  time  there 
had  evidently  occurred  in  himself  a  gradual  process  of 
adjustment,  for  he  felt  quite  well.  At  this  stage  he  in- 
vited another  person  to  come  into  the  chamber  with  him, 
and  he  had  the  satisfaction  of  observing  the  immediate 
development  of  blueness  and  the  other  symptoms  of 
oxygen  collapse  in  his  companion. 

Evidently  acclimatization  is  a  very  real  phenomenon 
and  of  the  utmost  importance  to  any  one  exposed  to  a 
lowered  tension  of  oxygen. 

As  we  observed  it  in  ourselves  during  our  stay  on 
Pike's  Peak  acclimatization  consists  in  three  chief  alter- 
ations: (i)  increased  number  of  red  corpuscles  in  the 
blood;  (2)  some  change  in  the  lungs  or  blood  (Haldane 
considers  it  the  secretion  of  oxygen  inward  by  the  pul- 
monary tissue)  which  aids  the  absorption  of  oxygen,  and 
(3)  a  lowering  of  the  CO2  in  the  alveolar  air  of  the 
lungs.  This  lowering  of  the  CO2  in  the  lungs  is  bound  up 
with  increased  volume  of  breathing.  It  is  the  concomitant 
of  a  decreased  alkaline  reserve  in  the  blood  just  as  in 
nephritis  and  diabetes.  Acclimatization  in  this  respect 
consists  therefore  in  the  development  of  a  condition  which 
would  nowadays  be  called  acidosis. 

All  of  these  changes  are  of  a  quantitative  character. 
Miss  FitzGerald  ^  has  supplemented  the  results  obtained 
on  Pike's  Peak  by  an  extensive  series  of  careful  observa- 
tions on  the  inhabitants  of  towns  of  closely  graded  alti- 
tude from  sea  level  up  to  that  of  the  highest  inhabited 
place  in  our  western  country.  She  has  thus  shown  that 
the  mean  hemoglobin  and  the  mean  alveolar  CO2  of  the 
inhabitants  of  any  town  are  functions  of  the  mean  baro- 
metric pressure  of  the  place. 

5  FitzGerald,  M.  P.,  Phil  Trans.,  1913,  B.  203,  p.  351,  and  Proc. 
Royal  Soc,  1914,  B.  88,  248. 


loo  CONTEMPORARY  SCIENCE 

I  shall  not  discuss  pulmonary  oxygen  secretion  now, 
because  the  problem  is  still  extremely  obscure;  nor  the 
increased  production  of  red  blood  corpuscles,  which  is  a 
slow  process  requiring*  weeks  for  completion,  and  play- 
ing no  considerable  part  in  the  matter  particularly  before 
us. 

We  will  fix  our  attention  upon  the  fact  that  both  the 
alveolar  CO2  of  the  pulmonary  air  and  the  alkaline  re- 
serve of  the  blood  are  reduced  in  accurate  adjustment  to 
any  altitude,  or  oxygen  tension,  to  which  a  man  is  sub- 
jected for  a  few  days  or  even  a  few  hours.  This  func- 
tional readjustment  is,  I  believe,  of  great  significance  in 
relation  to  aviation,  since  it  involves  a  larger  volume  of 
breathing  per  unit  mass  CO2  eliminated :  it  thus  compen- 
sates in  part  for  the  rarefaction  of  the  air. 

But  how  is  it  brought  about  ?  And  why  are  the  changes 
of  breathing  gradual,  when  the  changes  of  altitude  and 
oxygen  tension  are  abrupt?  The  answer  lies  in  part  at 
least  in  the  mode  of  development,  and  the  nature  of  that 
acidosis  of  altitude  to  which  I  have  referred.  It  is 
scarcely  necessary  to  remind  you  that,  as  L.  J.  Henderson 
has  shown,  the  balance  of  acids  and  bases  in  the  blood, 
its  Ch,  depends  upon  the  maintenance  of  a  certain  ratio 
between  the  dissolved  carbonic  acid,  H2CO3  and  sodium 
bicarbonate,  NaHCOg,  or  as  Van  Slyke  terms  it,  the  alka- 
line reserve.  On  the  basis  of  this  conception  the  prevalent 
view  of  acidosis  is  that,  when  acids  other  than  carbonic 
are  produced  in  the  body,  the  bicarbonate  is  in  part  neu- 
tralized. The  alkaline  reserve  is  thus  lowered,  and  the 
carbonic  acid  of  the  blood  being  now  in  relative  excess, 
an  increased  volume  of  breathing  is  caused  as  an  effort  at 
compensation. 

Recent  investigations  ®  by  Dr.  H.  W.  Haggard  and 
myself  show  that  an  exactly  opposite  process  is  likewise 
possible.    We  find  that  whenever  respiration  is  excited  to 

6  Henderson  and  Haggard,  Jour.  Biol.  Chem.,  1918,  pp.  333 
345,  355,  365. 


THE  PHYSIOLOGY  OF  THE  AVIATOR     107 

more  than  ordinary  activity,  and  the  carbonic  acid  of  the 
blood  is  thus  reduced  below  the  normal  amount,  a  com- 
pensatory fall  of  the  alkaline  reserve  occurs.  The  body 
is  evidently  endowed  with  the  ability  to  keep  the  ratio 
of  H2CO3  to  NaHCOg  normal,  not  only  by  eliminating^ 
CO2  when  the  alkali  is  neutralized,  but  also  by  the  passage 
of  sodium  out  of  the  blood  into  the  tissue  fluid  (or  by 
some  equivalent  process)  to  reduce  the  alkaline  reserve. 
A  loss  of  CO2  during  over-active  breathing  is  thus  bal- 
anced.  If  it  were  not  balanced  a  state  of  alkalosis  would 
occur,  which  would  inhibit  and  induce  a  fatal  apnoea. 

It  is  really  in  this  way  I  believe  that  some  of  those  con- 
ditions arise  which  nowadays  are  called  "acidosis."  If 
so  they  are  not  truly  acidosis,  or  rather  the  process  pro- 
ducing them  is  not  acidosis,  although  the  resultant  con- 
dition gives  some  of  the  most  characteristic  tests  of  this 
condition.  It  is  on  the  contrary  a  state,  or  rather  a 
process,  which  Mosso  was  the  first  to  recognize,  although 
obscurely,  and  which  he  termed  "acapnia"  an  excessive 
elimination  of  COg.  Recent  papers  "^  from  my  laboratory 
have  shown  that  a  sudden  and  acute  acapnia  induces  pro- 
found functional  disturbances,  including  circulatory  fail- 
ure. 

It  is  one  of  the  well-known  facts  in  physiology  that 
deficiency  of  oxygen,  or  anoxemia,  causes  an  "acidosis." 
Recent  and  as  yet  unpublished  work  of  Dr.  Haggard  and 
myself  indicates  that  the  process  involved  is  almost  dia- 
metrically the  opposite  of  that  which  has  heretofore  been 
supposed  to  occur,  and  that  the  result  is  not  a  true  acido- 
sis. Under  low  oxygen,  instead  of  the  blood  becoming- 
at  first  more  acid  with  a  compensatory  blowing  off  of 
CO2,  what  actually  occurs  is  that,  as  the  first  step,  the 
anoxemia  induces  excessive  breathing.  This  lowers  the 
CO2  of  the  blood,  rendering  it  abnormally  alkaline;  and 

■^  Henderson  and  Harvey,  Amer.  Jour.  Physiol.,  1918,  46,  p. 
533,  and  Henderson,  Prince  and  Haggard,  Jour,  Pharmac,  Ex^ 
per,  Therap.,  1918,  11,  p.  189. 


io8  CONTEMPORARY  SCIENCE 

alkali  passes  out  of  the  blood  to  compensate  what  would 
otherwise  be  a  condition  of  alkalosis. 

We  regard  the  current  explanation,  based  on  the  pro- 
duction of  lactic  acid,  as  needing  reversal. 

The  application  of  this  idea  to  the  changes  of  breath- 
ing and  of  the  blood  alkali  in  acclimatization  clears  up 
some  of  the  points  which  heretofore  have  been  obscure. 
Thus  on  Pike's  Peak  we  saw  that  persons  whose  breathing 
under  the  stimulant  of  oxygen  deficiency  increased  quickly 
to  the  amount  normal  for  the  altitude  suffered  correspond- 
ingly little,  while  those  whose  respiratory  center  was  rela- 
tively insensitive  to  this  influence  suffered  severely.  The 
one  type  readily  developed  the  acapnia  and  in  consequence 
the  pseudo-acidosis  which  the  altitude  requires.  The 
other  did  not. 

Here  let  me  pause  a  moment  to  bring  these  conceptions 
into  some  degree  of  harmony  with  fundamental  doctrines 
regarding  respiration.  For  more  than  a  century,  in  fact 
•ever  since  the  days  of  Lavoisier,  the  argument  has  been 
active  whether  our  breathing  is  controlled  by  oxygen  need 
or  by  the  output  of  COg.  For  the  past  thirty  years,  and 
especially  during  the  last  ten  or  twelve,  the  theory  of  regu- 
lation by  CO2,  or  in  its  later  form  by  C,  has  held  the 
field.  Indeed  it  is  established  now — almost  beyond  the 
possibility  of  contradiction,  it  would  seem — ^that  during 
any  brief  period  of  time,  and  under  conditions  to  which 
the  individual  is  accustomed,  the  amount  of  CO2  produced 
in  the  tissues  of  the  body,  through  its  influence  on  the  Ch 
of  the  blood,  is  the  factor  controlling  the  volume  of  air 
breathed.    Its  effects  are  immediate. 

But  when  we  view  the  matter  more  broadly  it  is  clear 
that  this  is  by  no  means  the  whole  story.  The  oxygen 
tension  of  the  air  is  the  influence  which  determines  just 
how  sensitive  the  respiratory  center  is  to  excitement  by 
CO2.  But  the  effects  of  any  change  of  oxygen  tension 
are  slow  in  developing,  requiring  in  some  persons,  as  we 
:saw  on  Pike's  Peak,  hours  to  begin  and  several  days  to 


THE  PHYSIOLOGY  OF  THE  AVIATOR    109 

become  complete.  In  fact  there  are  many  perfectly 
healthy  persons  who,  if  caused  to  breathe  progressively 
lowered  tensions  of  oxygen  down  to  6  or  7  per  cent,  in 
the  course  of  half  an  hour,  feel  nothing.  Their  breathing 
shows  no  considerable  augmentation.  They  simply  lose 
consciousness,  and  if  left  alone  they  would  die,  without 
any  apparent  effort  on  the  part  of  respiration  to  compen- 
sate for  the  deficiency  of  oxygen.  In  such  persons  the 
stimulant  of  oxygen  deficiency  exerts  only  a  slowly  de- 
veloping influence  upon  the  sensitiveness  of  the  respira- 
tory  center  to  the  stimulus  of  COg.  They  can  become  ac- 
climatized to  great  altitude  only  at  the  cost  of  prolonged 
mountain  sickness.  Evidently  they  are  not  suited  to  be 
aviators. 

In  very  sensitive  subjects,  on  the  contrary,  the  period 
of  readjustment  is  much  shorter.  It  is  a  matter  not  of 
days  but  of  hours,  and  the  functional  alterations  begin 
to  develop  almost  immediately  even  under  slight  oxygen 
deficiency.  The  upper  air  is  for  those  men  whose  organi- 
zation readily  responds  with  vigorous  compensatory  re- 
action. 

With  this  inadequate  sketch  of  present  scientific 
knowledge  regarding  life  at  great  altitudes  as  a  back- 
ground, we  may  turn  to  the  application  of  this  knowledge 
to  the  problems  of  human  engineering  in  the  aviation 
service  of  our  army  during  the  war.  In  September,  1917, 
I  was  appointed  chairman  of  the  Medical  Research  Board 
of  the  Air  Service  and  was  asked  to  lay  out  a  plan  for 
the  development  of  a  method  of  testing  the  ability  of 
aviators  to  withstand  altitude. 

You  will  readily  guess  the  line  along  which  one  would 
attack  such  a  problem.  It  consisted  in  the  development 
of  an  apparatus  from  which  the  man  under  test  breathes 
air  of  a  progressively  falling  tension  of  oxygen.  The 
particular  form  which  we  use  is  called  a  rebreathing  ap- 
paratus. It  consists  of  a  steel  tank  holding  about  lOO 
liters  of  air,  connected  with  a  small  spirometer  to  record 


no  CONTEMPORARY  SCIENCE 

the  breathing,  and  a  cartridge  containing  alkali  to  absorb 
the  CO2  which  the  subject  exhales.  Breathing  the  air  in 
this  apparatus  through  a  mouthpiece  and  rubber  tubing 
the  subject  consumes  the  oxygen  which  it  contains,  and 
thus  produced  for  himself  the  progressively  lower  and 
lower  tensions  of  oxygen  which  are  the  physiological 
equivalent  of  altitude.  To  control  and  test  the  accuracy 
of  the  results  with  the  rebreathing  apparatus  we  installed 
in  our  laboratory  at  Mineola  a  steel  chamber,  in  which 
six  or  eight  men  together  can  sit  comfortably,  and  from 
v^hich  the  air  can  be  exhausted  by  a  power  driven  pump 
down  to  any  desired  barometric  pressure. 

Such  apparatus  was,  however,  only  the  beginning.  The 
practical  problem  was  to  determine  the  functional  changes 
— ^pulse  rate,  arterial  pressure,  heart  sounds,  muscular 
coordination  and  psychic  condition  occurring  in  the  good, 
the  average  and  the  poor  candidates  for  the  air  service, 
and  then  to  systematize  and  introduce  these  standards  on 
a  very  large  scale  at  the  flying  fields  in  this  country  and 
in  France. 

That  this  program  was  successfully  carried  through, 
and  was  approaching  completion  when  the  armistice  was 
signed,  was  due  chiefly  on  the  scientific  side  to  the  bril- 
liant work  of  my  colleagues  Majors  E.  C.  Schneider,  J.  L. 
Whitney,  Knight  Dunlap  and  Captain  H.  F.  Pierce,  and 
on  the  administrative  side  to  the  splendid  cooperation  of 
Colonel  W.  H.  Wilmer  and  Lieutenant-Colonel  E.  G. 
Seibert. 

We  have  recently  published  a  group  of  papers,®  brief 
l)Ut  fairly  comprehensive  in  their  technical  details,  and  I 
shall  not  now  repeat  what  has  there  been  said,  but  shall 
confine  myself  to  a  few  salient  points.  One  of  these  is  a 
final  and  striking  demonstration  of  our  main  thesis. 
Schneider  and  Whitney  went  into  the  steel  chamber  and 

8Y.  Henderson,  E.  G.  Seibert,  E.  C.  Schneider,  J.  L.  Whitney, 
K.  Dunlap,  W.  H.  Wilmer,  C.  Berens.  E.  R.  Lewis  and  S.  Paton, 
Journal  American  Medical  Association,  1918,  Vol.  71,  pp.  1382- 
1400. 


THE  PHYSIOLOGY  OF  THE  AVIATOR     iii 

the  air  was  pumped  out  of  it  until  the  barometer  stood  at 
only  i8o  mm.,  23  per  cent,  of  the  pressure  outside:  the 
equivalent  of  an  altitude  of  35,000  feet.  Throughout  the 
test  they  were  supplied  with  oxygen  from  a  cylinder 
through  tubes  and  mouth-pieces.  They  experienced  no 
discomfort  except  from  flatus :  the  gases  of  the  stomach 
and  intestine  of  course  expanded  nearly  five-fold. 

In  comparison  with  this  observation  is  to  be  placed  the 
recent  record  ascent  by  Captain  Lang  and  Lieutenant 
Blowes  in  England  to  a  height  of  30,500  feet.  They  were 
supplied  with  oxygen  apparatus;  but  a  defect  developed 
in  the  tube  supplying  Lieutenant  Blowes  and  he  lost  con- 
sciousness. Captain  Lang  seems  to  have  suffered  only 
from  cold. 

From  this  it  might  appear  that  the  simplest  way  to 
solve  the  problem  of  lofty  ascents  would  be  by  means  of 
oxygen  apparatus.  The  Germans  evidently  made  use  of 
such  apparatus,  for  it  was  found  in  the  wreck  of  one  of 
the  German  planes  shot  down  over  London.  The  British 
also  had  such  apparatus,  but  it  was  difficult  to  manufac- 
ture, wasteful  in  operation,  and  in  other  respects  left 
much  to  be  desired.  In  fact  the  devising  of  such  appara- 
tus and  its  adaptation  to  the  peculiar  requirements  of  the 
human  wearer  are  a  problem  which  can  be  solved  only 
by  the  close  cooperation  of  a  physiologist  and  a  mechani- 
cal engineer.  Mr.  W.  E.  Gibbs,  of  the  Bureau  of  Mines, 
with  whom  I  had  cooperated  in  developing  mine  rescue 
oxygen  apparatus,  took  up  this  problem  and  produced  a 
device  which  should  prove  valuable.  Unfortunately  the 
common  tendency  to  favor  ideas  and  apparatus  coming 
to  us  from  Europe  operated  against  the  adoption  of  the 
better  American  device. 

It  is  doubtful,  however,  whether  any  apparatus  of  this 
sort  will  ever  quite  take  the  place  of  physical  vigor  and 
capacity  to  resist  oxygen  deficiency  on  the  part  of  the 
aviator  himself.  Imagine  him,  when  fighting  for  his  life 
above  the  clouds,  handicapped  by  goggles  over  his  eyes. 


112  CONTEMPORARY  SCIENCE 

wireless  telephone  receivers  on  his  ears,  a  combined  tele- 
phone transmitter  and  oxygen  inhaler  over  his  mouth,  and 
a  padded  helmet  on  his  head  I 

The  importance  of  determining  the  aviator's  inherent 
power  of  resistance  to  oxygen  deficiency,  if  he  is  to  be 
even  for  a  few  moments  without  an  oxygen  inhaler,  is 
demonstrated  by  the  results  of  the  routine  examinations 
made  with  the  rebreathing  apparatus  in  the  laboratory. 
These  results  show  that  15  to  20  per  cent,  of  all  the  men 
who  pass  an  ordinary  medical  examination  are  unfit  to 
ascend  to  the  altitudes  now  required  of  every  military 
aviator.  On  the  other  hand  these  tests  pick  out  a  small 
group  of  5  to  10  per  cent.,  who,  without  apparent  im- 
mediate physical  deterioration,  withstand  oxygen  defici- 
ency corresponding  to  altitudes  of  20,000  feet  or  more. 

It  is  particularly  interesting  to  note  that  when  the  re- 
breathing  test  is  pushed  beyond  the  limit  that  the  man 
can  endure,  be  it  the  equivalent  of  only  10,000  or  25,000, 
two  different  physiological  types  with  all  gradations  be- 
tween them  are  revealed.  The  fainting  type  collapses 
from  circulatory  failure  and  requires  an  hour  or  two  to 
recover.  Often  the  heart  appears  distinctly  dilated.  The 
other  and  better  type,  on  the  contrary,  goes  to  the  equiva- 
lent of  a  tremendous  altitude  on  the  rebreathing  appara- 
tus and  loses  consciousness,  becoming  glassy-eyed  and 
more  or  less  rigid,  but  without  fainting.  When  normal 
air  is  administered  such  men  quickly  recover. 

Perhaps  I  ought  to  say  at  least  a  few  words  regarding 
the  other  aspects  of  the  work  at  Mineola:  for  example 
the  valuable  psychological  investigations  and  the  contro- 
versy over  the  rotation  tests,  which  have  figured  so  largely 
in  our  medical  journals  of  late.  It  seemed  best,  however, 
to  confine  myself  this  evening  to  my  own  special  field. 
Nevertheless  I  cannot  suppress  a  public  expression  here 
of  my  sympathy  for  the  brave  and  able  scientific  men  in 
the  psychological  group  at  Mineola,  who  insisted  on  in- 
vestigating the  validity  of  the  rotation  tests.     I  am  sure 


THE  PHYSIOLOGY  OF  THE  AVIATOR     113 

tfiat  you  will  feel  as  I  do,  when  I  tell  you  that  they  were 
threatened  with  punishment  for  insubordination  when 
they  refused  to  recognize  that  a  regulation  of  the  army, 
which  prescribes  the  duration  of  nystagmus  after  the  ro- 
tation test,  necessarily  makes  this  a  physiological  fact. 

I  would  gladly  devote  a  few  minutes  also  to  pointing 
out  some  of  the  lessons  to  be  drawn  from  the  rather  un- 
usually good  opportunities  which  fell  to  my  lot  to  observe 
the  mingling  of  science  and  militarism.  The  chief  lesson 
can  be  put  in  a  single  phrase :  They  do  not  mix.  The  War 
Gas  Investigations,  which  formed  the  nucleus  on  which 
the  Chemical  Warfare  Service  finally  developed,  and 
the  Medical  Aviation  Investigations,  of  which  I  have 
spoken  this  evening,  were  both  successful  largely  be- 
cause at  first  they  were  developed  under  civilian  control, 
under  that  splendid  scientific  arm  of  the  government,  the 
Bureau  of  Mines  and  its  able  director.  It  is  a  wise  pro- 
vision of  our  government  by  which  the  Secretary  and 
Assistant  Secretaries  of  War  are  always  civilians.  It 
would  also  be  wise  for  the  general  staff  in  any  future  war 
to  keep  scientific  men  on  a  scientific  status  instead  of 
practically  forcing  them  into  uniform. 

We  all  hope  that  we  are  done  with  war,  and  with  sol- 
diers— at  least  for  a  generation.  We  can,  however,  derive 
certain  broad  lessons  applicable  to  the  conditions  of  peace 
from  the  experiences  and  intense  activities  of  war,  when 
almost  unlimited  funds  were  obtainable  for  research  and 
the  experiences  ordinarily  scattered  over  years  were 
crowded  into  a  few  months.  One  of  these  lessons  is  that 
scientific  men  need  to  develop  the  capacity  to  become  the 
heads  of  large  enterprises  without  ceasing  to  be  scientific, 
without  degenerating,  as  is  too  often  the  case,  into  the 
super-clerk,  who  seems  to  be  the  American  ideal  of  the 
high  executive  ofiicial.  It  is  not  enough  for  the  scientific 
man  to  become  the  expert  adviser  to  the  unscientific  ad- 
ministrator. If  the  latter  has  the  responsibility  he  will 
use  his  power  as  he,  and  not  as  the  scientific  man,  sees 


114  CONTEMPORARY  SCIENCE 

fit.  To  this  rule  I  have  known  only  one  splendid  excep- 
tion. 

For  the  most  part  among  us  the  great  prizes  go  to  the 
man  who  works  up  through  clerical  rather  than  through 
expert  lines.  We  must  find  some  way  to  change  this. 
The  path  of  science  must  lead  to  the  top,  and  at  the  top 
must  still  be  science.  To  achieve  this  ideal,  the  scientist 
must  show  generosity  toward  colleagues  and  subordinates, 
an  enthusiastic  recognition  of  their  merit  and  an  abne- 
gation of  self-aggrandizement,  no  less  than  skill  in  plan 
and  energy  in  execution.  It  is  essential  also  that  he 
should  develop  methods  for  conserving  time  and  strength 
by  assigning  clerical  work  to  clerks  instead  of  becoming  a 
clerk  himself,  in  order  that  he  may  keep  mind  and  desk 
clear  for  the  really  important  things. 

The  Chemical  Warfare  Service  was  a  success  largely 
because  the  chief  of  the  Research  Division  followed  these 
principles  as  the  spontaneous  promptings  of  science  and 
patriotism.^  Medical  research  in  aviation  was  produc- 
tive just  so  long  as  it  pursued  a  similar  course. 

He  who  charts  this  course,  so  that  others  may  follow  it 
through  the  pathless  seas  of  the  future,  will  make  a  great 
contribution  to  science,  education,  government,  and  in- 
deed to  nearly  every  phase  of  trained  activity  in  America. 

9  Cf.  G.  A.  Burrell,  Journal  of  Industrial  and  Engineering 
Chemistry,  1918,  Vol.  XL,  p.  93. 


TWENTY-FIVE    YEARS    OF   BACTERIOL- 
OGY: A  FRAGMENT  OF  MEDICAL 
RESEARCH 

(Address  of  the  President  of  the  American  As- 
sociation for  the  Advancement  of  Science,  Chi- 
cago, 1920) 

BY 

Simon  Flexner 
Rockefeller  Institute 

IMMUNITY 

Just  a  quarter  of  a  century  ago,  that  is  in  1895,  ^^ 
announcement  was  made  at  the  67th  meeting  of  the  Ger- 
man Society  of  Naturalists  and  Physicians  that  diphtheria, 
one  of  the  most  severe  and  fatal  diseases  of  mankind,  had 
been  conquered  by  means  of  an  antitoxin.  This  great 
event  is  a  landmark,  not  alone  in  the  history  of  medicine, 
but  also  in  the  history  of  the  world,  and  it  provides  a  high 
peak  of  achievement  from  which  the  growth  of  bacteriol- 
ogy may  be  viewed.  In  order  that  we  may  follow  the 
growth  with  understanding,  it  is  necessary,  at  first,  to 
cast  a  glance  backward  before  we  begin  on  the  narrative, 
the  aim  of  which  is  to  bring  us  to  the  state  of  knowledge 
of  bacteriology  existing  in  our  own  day. 

Since  disease  is  so  universal  a  phenomenon  and  com- 
municability  from  individual  to  individual  so  obvious  an 
incident  of  its  epidemic  prevalence,  the  conception  of  a 

IIS 


ii6  CONTEMPORARY  SCIENCE 

contagium  vivim  or  antmatum  and  hence  of  an  invisible 
form  of  life  as  the  initiator  of  the  condition,  can  be  traced 
far  back  in  the  written  records  of  human  events.  And 
yet  it  was  not  until  about  1850  that  a  microscopic  body, 
which  we  would  now  call  a  bacterium,  was  actually  de- 
tected in  the  blood  of  a  sick  animal.  The  anthrax  bacillus, 
as  it  has  since  been  named,  which  is  now  recognized  as 
the  inciting  microbe  of  splenic  fever,  was  destined  to  play 
a  leading  part  in  the  development  of  the  future  science 
of  bacteriology,  but  at  this  early  period  its  full  meaning 
was  not  perceived.  When,  however,  in  1863  Davaine 
succeeded  in  communicating  splenic  fever  to  a  healthy 
animal  by  the  direct  inoculation  of  blood  containing  the 
anthrax  bacillus,  the  science  of  bacteriology  may  be  said 
to  have  been  bom. 

The  dates  are  significant  to  one  who  wishes  to  follow 
the  march  of  events  which  brought  the  greatest  master 
of  all,  Pasteur,  into  the  field  of  microbiology  and  led  him 
on  to  the  study  of  the  infectious  diseases,  first  of  animals 
and  then  of  man.  For  on  looking  backward  we  find  that 
coincidental  with  Davaine's  epochal  experiments,  Pas- 
teur was  already  engaged  on  those  studies  of  fermenta- 
tion and  putrefaction  which  were  not  only  to  set  our 
conception  of  those  processes  on  a  secure  biological  foun- 
dation, but  as  an  important  side  effect  were  to  demolish, 
once  and  forever,  the  elaborately  constructed  but  inse- 
curely based  doctrine  of  the  spontaneous  generation  of 
microscopic  forms  of  life. 

For  Pasteur  it  was  but  a  step,  although  for  us  one 
of  the  highest  importance,  from  the  studies  in  fermenta- 
tion and  putrefaction  to  those  on  the  infectious  diseases 
in  which,  indeed,  the  great  triumphs  he  achieved  consist 
far  less  in  the  detection  of  new  kinds  of  microbes  to  which 
the  various  contagious  diseases  might  be  described,  than 
in  his  fundamental  discoveries  in  immunology,  or  the 
science  of  the  specific  prevention  of  disease. 

This  work  in  the  field  of  immunology,  first  opened  te 


TWENTY-FIVE  YEARS  OF  BACTERIOLOGY  117 

experimental  investigation  by  him,  is  the  aspect  of  Pas- 
teur's labors  to  which  I  wish  especially  to  direct  your  at- 
tention, since  it  forms  the  connecting  bond  between  the 
earliest  and  thus  the  oldest,  and  the  present  and  thus  the 
latest  discoveries  in  a  field  in  which  medical  science  has 
come  to  secure  some  of  its  most  notable  successes.  There 
can  be  no  doubt  that  the  discovery  in  1880  of  the  artificial 
immunity  to  fowl  cholera  came  not  as  a  direct  incident, 
but  rather  as  an  accidental  circumstance  to  the  experi- 
ments being  pursued.  In  after  years  Pasteur  loved  to 
point  out  the  importance  of  the  "prepared  mind'*  as  a 
requisite  of  the  investigator,  in  order  that  he  may  seize 
hold  of  and  utilize  in  respect  to  a  question  propounded  by 
experiment  what,  viewed  superficially,  appears  to  be  only 
an  indirect  and  misleading  answer.  The  advances  lead- 
ing rapidly  from  the  artificially  induced  immunity  in  fowl 
cholera  to  the  dramatic  and  historically  and  economically 
important  immunity  in  anthrax  and  to  the  humanly  im- 
portant immunity  in  rabies,  involved  no  strictly  new  con- 
ceptions on  Pasteur's  part.  They  consisted  merely  of  the 
carrying  forward  of  the  ideas,  often  ingeniously  modi- 
fied, derived  from  the  study  of  the  sources  of  the  condi- 
tion of  immunity  in  fowl  cholera. 

But  should  we  inquire  to  what  order  of  events  already 
known  this  phenomenon  of  artificial  immunity  belongs, 
we  should  say  at  once  probably  to  the  order  having  to  do 
with  the  Jennerian  vaccination  against  smallpox.  As 
every  one  knows,  vaccination  against  smallpox  consists 
in  the  utilization  of  human  smallpox  material  which  has 
become  modified  by  passing  through  the  cow,  in  which  it 
sets  up  the  condition  named  cowpox.  When  this  modi- 
fied microbic  virus  of  the  disease  is  returned  to  man,  a 
mild  form  of  smallpox  is  induced,  which  suffices  through 
a  term  of  years  to  protect  the  individual  vaccinated,  so- 
called,  from  infection  with  the  more  active  or  virulent 
smallpox  virus. 

The  significance  of  the  new  observations  was  grasped 


Ii8  CONTEMPORARY  SCIENCE 

by  Pasteur  and  related  to  Jennerian  vaccination.  His 
great  discovery  then  consisted  in  the  determination  that 
pathogenic  or  disease-producing  microbes  may  be  modified 
otherwise  than  by  passing  through  foreign  and  relatively 
insusceptible  animal  species,  and  that  such  simple  agencies 
as  long  cultivation  in  vitro  (fowl  cholera),  high  tempera- 
tures and  therefore  non-optimal  conditions  of  growth 
(anthrax),  and  partial  drying  of  the  animal  material  car- 
rying the  microbe  (rabies),  would  suffice  so  to  modify 
and  attenuate  the  respective  microbes  that  upon  inocula- 
tion they  set  up  not  the  severe,  but  only  mild  states  of 
infection,  from  which  not  only  does  recovery  ensue,  but 
the  restored  animal  is  enduringly  protected  from  the  ordi- 
nary and  often  fatal  attacks  of  a  disease. 

Looking  backward  from  our  present  higher  position  of 
vantage,  we  may  discern  certain  minor  imperfections  in 
this  fundamental  work  on  artificial  immunity.  For  ex- 
ample, It  would  now  appear  that  the  so-called  attenuated 
cultures  of  the  bacillus  of  fowl  cholera,  used  for  purposes 
of  immunization,  were  not  so  much  attenuated  as  actually 
dead,  and  that  the  material  inoculated  consisted  of  a  mix- 
ture of  dead  bacilli  and  their  metabolic  and  disintegrative 
products.  In  other  words,  it  seems  that  Pasteur  without 
perceiving  it  had  discovered  not  only  a  principle  of  wide 
applicability  in  inducing  artificial  immunity,  but  a  gen- 
eral method  of  utilizing  dead  bacteria  as  vaccines,  and 
one  which  in  more  recent  times  has  been  widely  resorted 
to  in  preventing  outbreaks  of  typhoid  fever,  cholera,  and 
some  other  diseases. 

In  1882  antirabic  inoculation  was  perfected.  Pasteur 
had,  of  course,  reflected  deeply  on  the  sources  of  the  im- 
mune state  and  in  explanation  of  it  he  inclined  to  the 
view  that  the  basis  of  the  phenomenon  was  a  nutritive 
condition.  He  conceived  that  in  the  course  of  that  form 
of  microbic  development  within  the  body  which  came  to  a 
spontaneous  end  and  left  the  individual  protected,  certain 
essential  foodstuflfs  were  consumed,  in  virtue  of  which 


TWENTY-FIVE  YEARS  OF  BACTERIOLOGY  119 

the  same  variety  of  microbe  could  not  later  gain  another 
foothold.  Time  has  not  upheld  this  simple  conception; 
but  when  it  was  formulated  the  subject  matter  of  bacteri- 
ology was  still  too  fragmentary  and  scanty  to  point  to  the 
deeper  underlying  chemical  and  biological  processes  in- 
volved. Indeed,  nearly  ten  years  elapsed  until  Behring's 
discovery  of  antitoxic  immunity  brought  about  a  revolu* 
tion  in  the  prevailing  ideas  and  opened  up  new  and  fas- 
cinating vistas  of  research. 

We  have  now  reached  the  period  at  which  the  German 
school  of  bacteriology^  led  by  Robert  Koch,  has  arisen 
beside  the  French.  Koch's  career  in  science  was  meteoric. 
From  an  inconspicuous  country  practitioner  he  became, 
in  the  period  beginning  about  1880,  the  outstanding  world 
figure  in  bacteriology.  But  his  greatest  work  was  com- 
pleted in  relatively  few  years,  although  that  of  his  pupils 
has  continued  up  to  and  is  still  potent  at  the  present  day. 
It  is  informing  to  reflect  that  just  as  Davaine  made  the 
first  signal  advance  in  the  experimental  inoculation  of 
disease  with  the  anthrax  bacillus,  and  Pasteur  the  first 
dramatic  demonstration  of  the  practicability  of  protective 
inoculation  with  bacterial  cultures  also  with  that  bacillus, 
Koch  rose  into  fame  through  the  study  of  its  life  history 
by  direct  observation  under  the  microscope.  But  Koch's 
greater  contribution  to  bacteriology  consisted  of  a  method 
of  cultivation  so  perfected  that  pure  growths  of  bacterial 
species  were  readily  obtainable.  The  consequence  was 
that  in  a  very  brief  period  of  years  a  whole  host  of  patho- 
genic bacteria  or  incitants  of  diseases  of  man  and  animals 
was  secured,  among  which  were  the  highly  important 
bacilli  of  tuberculosis,  cholera,  typhoid  fever,  diphtheria, 
tetanus,  dysentery,  plague,  meningitis  and  many  others. 

Up  to  the  period  we  are  now  considering,  all  the  dis- 
eases of  microbic  origin  thus  far  investigated  successfully 
belonged  to  the  class  in  which  the  bacteria  invaded  the 
blood  and  the  internal  organs.  But  now  we  are  about  to 
learn  of  another  kind  of  disease  induced  by  a  class  of 


120  CONTEMPORARY  SCIENCE 

bacteria  which  are  peculiar  in  that  they  do  not  migrate 
throughout  the  body  but  remain  fixed  in  a  special  tissue 
or  part,  where  they  multiply  and  secrete  a  poison  which 
finds  its  way  first  into  the  lymph,  then  into  the  blood  and 
the  organs  generally.  This  latter  class  of  microbes  pro- 
duces its  effects  to  which  we  give  the  name  of  disease, 
and  of  which  diphtheria  and  tetanus  are  examples,  through 
the  operation  of  a  poison,  peculiar  to  each,  and  in  each 
instance  attacking  by  preference  certain  definite  organs  or 
parts  of  them.  Thus  the  poison  elaborated  by  the  diph- 
theria bacillus  selects  especially  the  lymphatic  organs, 
heart  and  nervous  system  for  its  action,  and  the  tetanic 
poison  the  nerve  cells  governing  muscular  contraction. 

We  have  now  returned  by  a  route  somewhat  circuitous 
perhaps  to  the  point  from  which  we  started,  namely  diph- 
theria and  its  antidote.  But  in  the  course  of  the  journey 
we  have  taken,  new  points  of  view  have  been  gained 
which,  as  will  appear,  are  to  transform  entirely  the  out- 
look upon  the  problems  that  bacteriologists  set  themselves 
to  solve. 

Behring  and  Kitasato  chose  the  task  of  inducing  in  ani- 
mals immunity,  to  diphtheria  on  the  one  hand  and  to 
tetanus  on  the  other.  This  was  a  logical  undertaking  and 
one  clearly  in  the  spirit  of  the  times.  Both  men  had  a 
strong  interest  in  the  quest.  The  one  (Behring)  was 
deeply  engaged  in  the  investigation  of  the  chemical  disin- 
fectants and  conceived  ideas  of  modifying  bacterial  growth 
through  these  agents,  as  Pasteur  had  succeeded  in  accom- 
plishing with  physical  means.  The  other  (Kitasato)  had 
succeeded  where  his  predecessor  and  the  discoverer  of  the 
tetanus  bacillus,  Nicolaier,  had  failed  in  obtaining  pure 
cultures  of  that  microbe.  Moreover,  the  restricted  local 
development  of  the  two  bacilli  and  their  generally  poison- 
ous or  toxic  effects  aroused  in  them  an  eager  interest  in- 
tensified by  the  epochal  discovery  just  made  by  Roux  and 
Yersin  that  the  toxin  of  the  diphtheria  bacillus  was  read- 
ily separable  from  the  bacilli  producing  it  and  could  be 


TWENTY-FIVE  YEARS  OF  BACTERIOLOGY  121 

obtained  by  precipitation  in,  it  is  true,  an  impure  state 
but  one  in  which  its  poisonous  action  was  preserved.  In- 
deed, so  appalling"  did  its  poisonous  effect  prove  to  be  that 
these  investigators  could  not  imagine  any  other  non-living 
substance  than  an  enzyme  which  could  exhibit  such  active 
properties. 

The  isolation  of  the  diphtheria  toxin,  quickly  to  be  fol- 
lowed by  the  similar  isolation  of  the  tetanus  toxin,  was 
an  event  of  capital  importance  and  reacted  at  once  vigor- 
ously on  the  chemical  aspects  of  bacteriology  just  strug- 
gling into  the  light.  The  immediate  effect  of  the  study  of 
the  new  poisons,  called  toxalbumins,  was  to  discredit  a 
whole  series  of  pure,  crystalline  basic  substances  obtained 
not  long  before  from  a  wide  variety  of  bacteria,  to  which 
the  name  of  ptomaines  had  been  given.  Many  of  the 
ptomaines  were  possessed  of  poisonous  properties ;  but 
what  was  disconcerting  was  that  very  diverse  bacteria 
might  yield  identical  chemical  compounds  which,  there- 
fore, lacked  the  property  of  specificity,  an  essential  qual- 
ity of  bacterial  activity.  The  toxalbumins,  on  the  other 
hand,  which  even  to  this  day  have  not  been  secured  in  a 
chemically  pure  state,  exhibit  in  perfect  degree  the  prop- 
erty of  specificity  and  display  all  the  power  for  evil  an(l 
all  the  potential  possibilities  for  good  which  their  original 
and  respective  bacilli  possess ;  and  although  no  method  of 
chemical  identification  of  their  special  nature  is  available, 
yet  their  pathological  effects  and  immunological  activities 
serve  readily  and  accurately  to  distinguish  one  from  the 
other  and  to  indicate  their  origin. 

The  rendering  of  animals  immune  to  diphtheria,  on  the 
one  hand  and  to  tetanus  on  the  other,  proved  a  difficult 
but  not  impossible  task.  The  method  adopted  was  to 
admix  disinfectant  chemicals,  of  which  the  one  finally 
selected  was  iodin  trichlorid,  with  the  bacilli  to  be  injected 
under  the  skin  of  animals,  or  with  the  contents  of  the 
culture  flasks  at  the  end  of  the  incubation  period.  Ob- 
viously, the  intent  was  to  moderate  the  poisonous  action 


122  CONTEMPORARY  SCIENCE 

of  the  inoculated  material,  in  the  hope  that  a  mild  and 
not  fatal  infection  would  be  induced  from  which  recov- 
ery would  follow  leaving  the  treated  animal  immune. 

The  experiments  were  sometimes  successful,  and  as 
such  seem  merely  to  illustrate  a  variation  of  the  Pasteur- 
ian  method  of  inducing  immunity  which,  as  we  saw,  was 
not  distinct  in  principle  from  the  Jennerian  vaccination. 
But  the  break  with  the  past  was  none  the  less  imminent, 
for  Behring's  next  act  was  not  to  speculate  on  the  theory 
of  immunity  but  to 'perform  a  decisive  experiment.  It  is 
to  be  kept  in  mind  that  in  the  poisons  or  toxalbumins  of 
diphtheria  and  tetanus,  we  possess  the  essentially  active 
ingredients  of  the  respective  bacilli  and  that  the  body  at- 
tacked does  not  succumb  to  the  invading  bacilli  but  to  the 
action  of  the  toxins.  Hence,  Behring  turned  to  the  blood 
of  the  immune  animals  and  tested  it  for  neutralizing  power 
against  the  poisons,  and  discovered  antitoxin ;  he  injected 
the  blood  of  an  immune  into  the  body  of  a  normal  animal 
prior  to  inoculation  and  discovered  passive  immunization ; 
and  finally,  he  injected  the  blood  of  an  immune  animal 
into  animals  previously  inoculated  with  the  bacilli  of  diph- 
theria and  tetanus,  and  discovered  serum  therapy.  The 
day  for  speculation  on  what  constituted  the  immune  state 
had  now  definitely  passed,  and  the  time  had  arrived  for 
subjecting  the  phenomenon  to  experimental  study. 

The  fluids  or  "humors"  of  the  body,  to  employ  a  term 
made  respectable  by  age,  as  represented  by  the  serum  of 
the  blood,  had  been  shown  to  carry  the  immunity  prin- 
ciples, but  what  part  did  the  cells  of  the  body  play  in  the 
process  ?  Both  fluids  and  cells  were  now  submitted  to 
rigid  and  ingenious  scrutiny,  and  about  them  an  immense 
literature  has  grown  up.  Soon  the  students  in  the  field 
divided  into  two  camps,  namely,  one  led  by  Ehrlich,  de- 
fending the  humoral  doctrine,  the  other  led  by  Metchni- 
koff,  urging  the  cellular  or  phagocytic  doctrine.  The  con- 
flicts which  raged  about  these  concepts  were  always  ani- 
mated and  sometimes  even  bitter ;  but  the  ultimate  effect 


TWENTY-FIVE  YEARS  OF  BACTERIOLOGY  123 

was  to  extend  rather  than  to  retard  and  confound  knowl- 
edge. We  are  moving  now  in  more  peaceful  times,  the 
heat  of  the  earlier  conflicts  having  largely  subsided,  and 
it  may  be  stated  that  neither  the  one  nor  the  other  doctrine 
finally  triumphed,  but  that  the  humors  or  fluids  of  the 
body  on  the  one  hand  and  the  cells  on  the  other  have  come 
to  be  recognized  as  the  active  participating  factors  in  the 
immunity  process,  the  one  complementing  the  other. 
Where  the  phenomenon  is  one  purely  of  the  neutralization 
of  a  poison  or  toxin,  the  fluid  portion  of  the  blood  suflices ; 
where  also  the  process  is  relatively  the  simple  one  of  act- 
ing on  and  dissolving  a  bacterial  cell,  there  also  the  fluid 
may  suffice,  although  an  essential  element  in  the  process 
may  have  been  suppHed  by  the  white  blood  cells  at  the 
moment  of  their  withdrawal  from  the  body.  But  where 
the  bacteria  are  not  readily  disintegrated  and  dissolved, 
there  the  phagocytes  of  the  blood  and  tissues  come  into 
play  and,  through  their  power  of  engulfing  these  particles, 
operate  as  one  of  the  body's  main  defenses  against  in- 
fection. 

The  unraveling  of  the  intricacies  of  the  immune  state, 
following  upon  the  work  of  Behring,  has  brought  about 
a  sudden  and  unprecedented  enlargement  of  the  scope  of 
bacteriology,  as  well  as  supplied  a  wealth  of  new  facts 
of  which  many  have  permanently  enriched  practical  medi- 
cine and  opened  new  territory  to  profitable  exploration. 
It  may  suffice  at  this  point  merely  to  mention  certain  of 
the  devices  for  diagnosis  and  means  of  preventing  or  of 
treating  disease,  which  are  the  immediate  heritage  of 
studies  in  the  field  of  immunity,  of  which  many  have 
come  not  as  direct  fruits,  but  as  invaluable  by-products  of 
the  search.  In  this  manner  have  been  secured  the  Widal 
test  for  typhoid  fever,  the  Wassermann  and  allied  reac- 
tions, the  hypersensitive  or  Schick  test  for  diphtheria 
susceptibility,  the  hypersensitive  reaction  as  now  applied 
to  the  detecting  of  the  offending  agency  in  hay  fever  and 
allied  states,  the  refinements  of  bacterial  vaccination  in 


124  CONTEMPORARY  SCIENCE 

the  prevention  and  sometimes  in  the  treatment  of  dis- 
ease, and  so-called  specific  serum  therapy.  Moreover, 
these  studies  have  placed  in  the  hands  of  the  bacteriologist 
a  powerful  instrument  for  detecting,  through  immunity 
reactions  carried  out  in  test  tubes,  or  the  animal  body, 
new  varieties  of  pathogenic  or  disease-producing  bacteria 
and  of  investigating  more  closely  and  sorting  out  groups 
of  pathogenic  microbes  not  hitherto  subject  to  analysis. 
Finally,  the  immunity  reactions,  as  they  are  generically 
named,  have  been  found  not  to  be  restricted  to  bacterial 
cells  and  poisons,  but  to  apply  to  a  wide  variety  of  cells 
and  their  products.  For  it  should  be  recalled  that  in  the 
decade  immediately  succeeding  the  discovery  of  antitoxin, 
agglutinins,  precipitins,  bacteriolysins,  cytotoxins,  hemoly- 
sins, complements,  chemotaxis,  anaphylaxis,  and  the 
minutiae  of  phagocytosis  were  discovered  and  became  the 
objects  of  animated  and  of  ten, feverish  and  sometimes  con- 
troversial but  always  profitable  investigation. 

It  happened  also  and  quite  naturally  and  logically  that 
this  should  be  the  heyday  of  hypotheses  concerning  the 
biological  basis  of  immunity  and  the  manner  in  which  in- 
teraction takes  place  between  toxin  and  antitoxin  inside 
as  well  as  outside  the  body,  and  of  the  englobing  of  bac- 
teria and  other  bodies  by  the  blood  and  tissue  cells,  as 
well  as  the  nature  of  the  combinations  and  permutations 
and  reactions  between  the  more  complex  bacteria  and 
cells  in  course  of  their  immunological  transformations. 
And  thus  there  came  to  be  elaborated  the  side-chain  hy- 
pothesis of  Ehrlich,  which  vied  with  the  phagocytic  theory 
of  Metchnikoflf  as  well  as  with  the  adsorption  theory  of 
Bordet  and  the  physico-chemical  theory  of  Arrhenius. 
And  if  in  our  busy  lives  of  to-day  we  think  less  of  re- 
ceptors and  amboceptors,  of  complements  and  complemen- 
toids,  haptophorcs,  and  toxophores,  and  limit  ourselves 
somewhat  mor«  closely,  perhaps  even  a  little  too  exclu- 
sively, to  the  observed  fact  itself,  yet  it  is  well  that  we 
do  not  forget  how  great  at  the  time  was  the  stimulus  to 


TWENTY-FIVE  YEARS  OF  BACTERIOLOGY  125 

research  and  how  rich  the  booty  which  accrued  from  those 
labors  tinged  with  the  radiance  of  the  real  scientific 
imagination  of  an  Ehrlich,  a  Metchnikoff,  and  a  Bor- 
det. 

Not  all  the  high  expectations  of  practical  benefit  to  fol- 
low from  these  discoveries  have  been  realized,  but  some- 
times the  very  failures  have  been  turned  to  account  in 
opening  up  new,  or  illuminating  old,  avenues  of  progress. 
In  this  connection  it  is  instructive  to  recall  the  early  pro- 
nouncement of  Behring  made  two  years  after  the  discov- 
ery of  antitoxin,  and  while  he  was  under  the  influence 
doubtless  of  that  great  contribution : 

"The  present  state  of  the  immunity  question,"  he  says, 
''may  be  defined  as  follows :  Thus  far  no  generally  ap- 
plicable explanation  for  natural  immunity  has  been  forth- 
coming. But  of  the  artificially  produced  immunity  it  may 
be  said  that  the  precise  study  of  a  number  of  examples 
has  so  far  advanced  our  knowledge  that  we  may  assert 
with  confidence  that  the  immune  state  arises  from  a  pecu- 
liarity of  the  blood  and,  indeed,  of  its  cell-free  portion; 
in  no  instance  in  which  a  sufficiently  high  grade  of  im- 
munity has  been  attained  in  an  animal  species,  easily  sus- 
ceptible to  the  infection  in  question,  has  the  blood 
withdrawn  from  the  body  failed  to  show  evidences  of  the 
presence  of  the  immunity-conferring  substances." 

In  this  statement  will  be  perceived  the  extreme  humoral 
view  of  the  origin  of  immunity,  which  subsequent  inves- 
tigators failed  to  uphold.  But  he  continues  in  a  prophetic 
vein,  unfortunately  likewise  destined  not  to  be  wholly 
fulfilled. 

"With  the  achieving  of  this  standpoint  the  next  step 
in  the  winning  of  specific  curative  agents  for  the  infectious 
diseases  is  clearly  outHned:  all  that  is  required  is  the  in- 
duction in  a  susceptible  animal  species  of  a  high  degree 
of  artificial  immunity,  and  then  to  test  the  blood  for  the 
presence  of  protective  and  healing  substances." 

Time  has  exposed  the  fallacy  of  this  over-confident 


126  CONTEMPORARY  SCIENCE 

attitude  a::d  taught  the  distinction  between  the  two  va- 
rieties of  infectious  disease  and  their  corresponding  im- 
mune states,  according  as  their  main  effects  and  symptoms 
arise  from  the  toxalbumins  or  poisons  we  have  been  con- 
sidering, or  ,the  intimate  presence  within  the  organs  of 
the  microbes  themselves.  The  former  variety  chances 
indeed  to  be  in  the  minority,  and  hence  it  has  come  about 
that  the  diseases  to  be  successfully  combated  by  antitoxins 
are  few  in  number,  while  those  in  which  the  microbes 
penetrate  deeply  into  the  body  and  which  poison  its  tis- 
sues by  means  of  so-called  endotoxin,  are  far  more  num- 
erous. The  latter  class  includes  such  important  diseases 
as  tuberculosis,  typhoid  fever,  meningitis,  plague,  cholera, 
the  septicemias,  and  still  others.  And  yet  the  failures 
have  been  only  partial,  and  success  has  been  and  is  still 
being  won  against  odds  which  were  once  considered  in- 
superable. 

What  is  striking  is  the  capriciousness  with  which  the 
microbes  themselves  or  their  endotoxins  lend  themselves 
to  the  making  of  therapeutically  effective  serums,  as  con- 
trasted with  the  ease  and  certainty  of  action  in  this  re- 
spect of  the  toxalbumins.  All  the  latter  seem  capable  of 
yielding  abundant  antitoxins,  and  this  independently  of 
their  precise  source,  since  it  happens  that  toxalbumins  re- 
sembling those  of  bacterial  origin  exist  also  in  the  higher 
plants — as  in  the  castor  and  jequirity  beans — and  in  the 
venoms  of  reptiles  and  insects.  On  the  other  hand,  it 
has  not  thus  far  been  found  practicable  to  fashion  curative 
serums  for  tuberculosis,  typhoid  fever,  plague,  cholera, 
etc.,  while  success  has  been  achieved  in  the  instance  of 
epidemic  meningitis,  and  very  hopeful  results  have  re- 
cently been  attained  in  the  case  of  pneumonia. 

In  meningitis  the  success  is  linked  with  the  recognition 
of  a  second  principle  of'  action,  namely  the  advantage  to 
be  derived  from  what  may  be  called  the  local  specific 
treatment  of  a  disease,  or  the  bringing  of  the  healing 
serum  into  direct  and  intimate  relation  with  the  seat  of 


TWENTY-FIVE  YEARS  OF  BACTERIOLOGY  127 

the  infection  itself.  Since  in  epidemic  meningitis  it  is  the 
membranes  surrounding  the  brain  and  spinal  cord  and 
those  more  delicate  ones  lining  the  cavities  of  the  ventricles 
of  the  brain  which  are  the  seat  of  infection,  it  has  been 
found  easily  possible,  through  a  simple  and  safe  pro- 
cedure, to  inject  the  serum  into  the  cavity  of  the  spinal 
meninges,  whence  it  is  quickly  distributed  over  all  the 
membranes  of  the  brain  and  cord.  It  may  be  of  interest 
to  remark  that  it  is  not  practicable  to  reach  the  inflamed 
membranes  with  the  serum  by  way  of  the  blood,  since 
nature,  in  order  to  protect  the  sensitive  nerve  tissues  from 
injury  by  any  chance  deleterious  substance  in  this  fluid, 
has  interposed  an  impenetrable  barrier,  the  choroid  plexus, 
between  the  circulation  and  the  cerebrospinal  fluid  which 
bathes  and  sustains  the  nervous  organs,  and  which  is 
itself  elaborated  from  the  blood  by  this  plexus  with  ant 
accuracy  of  selectiveness  highly  remarkable. 

In  pneumonia  again  a  beginning  success  has  beenr 
achieved  through  a  finer  discrimination  of  specific  kinds/ 
among  the  pneumococci,  the  inciting  microbes  of  the  dis- 
ease. This  distinction  is  independent  of  ordinary  physi- 
ological and  cultural  characters  displayed  by  the  bacteria, 
which  do  not  serve  to  bring  out  the  underlying  specific 
properties  of  each,  and  has  been  accomplished  by  means 
of  the  so-called  immunity  tests  carried  out  in  test  tubes 
or  in  the  animal  body.  The  gain  to  practical  medicine 
from  the  detection  of  the  fundamental  differences  sub- 
sisting between  the  three  main  types  of  pneumococci  ex- 
isting in  this  country  has  been  very  great.  Already  a 
curative  serum  for  one  of  the  specific  types  of  pneumonia 
has  been  secured,  and  through  its  application  many  lives 
have  been  saved ;  while  beginnings  have  been  made  in  re- 
spect to  vaccination  against  the  disease  when,  as  some- 
times happens  in  institutions  and  in  communities,  epidem- 
ics prevail  and  claim  many  victims,  as  occurred  in  the 
Army  training  camps  during  the  measles  epidemic  of 
1917-18. 


128  CONTEMPORARY  SCIENCE 

Thus  we  have  learned  that  the  immunity  reactions,  or 
the  effects  on  bacteria  and  their  poisons,  of  the  fluid  and 
cells  of  the  body  as  modified  by  the  process  of  artificial 
immunization,  provide  more  delicate  and  precise  means  of 
discriminating  bacterial  species  than  the  qualities  of  form, 
growth  appearances  and  physiological  activities,  and  more 
accurate  methods  of  distinguishing  poisons  than  the  most 
refined  chemical  analyses ;  and  we  shall  learn  a  little  later 
in  connection  with  the  distinct  but  related  hypersensitive 
or  anaphylactic  state,  that  the  prepared  and  sensitized 
animal  body  responds  to  infinitesimal  amounts  of  protein 
matter  according  to  its  specific  origin,  in  a  manner  not 
otherwise  determinable  and  far  beyond  the  most  delicate 
laboratory  test  which  the  chemist  has  invented.  The  ani- 
mal body  thus, artificially  prepared,  or  as  sometimes  hap- 
pens naturally  sensitive,  acquires  an  appreciation  of  the 
inner  constitution  of  the  protein  molecule,  classifying  it, 
as  it  were,  not  only  according  to  its  ordinary  chemical 
nature,  but  according  to  its  species  origin. 

The  immunity  reactions  we  have  considered  are  not 
artificial  creations,  since  as  we  now  know,  they  are  the 
very  processes  which  nature  employs  in  her  unaided  ef- 
forts to  abate  infections,  and  when  need  be,  to  adopt  the 
body  to  foreign  proteins.  The  spontaneous  recovery  from 
infectious  disease,  by  which  is  meant  merely  that  the 
body  by  its  own  power  overcomes  the  microbes  and  their 
poisons,  depends  upon  the  setting  into  motion  of  the  series 
of  operations  through  which  immunity  responses  in  fluids 
and  cells  are  insured,  precisely  as  has  been  described  in 
the  event  of  an  artificial  immunization.  Hence  in  our 
efforts  at  serum  therapy  we  aim  merely  to  aid  "nature," 
by  introducing,  as  it  were,  into  the  beset  body  the  finished 
immunity  products  artificially  produced  in  healthy  ani- 
mals ;  and  in  protection  by  vaccination,  success  is  assured 
only  to  the  extent  to  which  the  healthy  body  has  been  com- 
pelled to  prepare  the  specific  immunity  substances  and  to 
hold  them  ready  at  hand  to  combat  the  entrance  through 


TWENTY-FIVE  YEARS  OF  BACTERIOLOGY  129 

its  outer  gateway  of,  for  instance,  such  microbes  as  those 
inciting  typhoid  fever  and  smallpox. 

That  it  is  through  the  prowess  of  the  body  itself,  and 
not  the  skill  and  art  of  the  physician,  that  recovery  from 
infectious  disease  takes  place,  had  already  become  evident 
to  the  ablest  physicians  of  nearly  one  hundred  years  ago. 
It  is  true  that  they  could  form  no  real  conception  of  the 
manner  in  which  the  cure  was  brought  about,  but  in  ad- 
mitting the  existence  of  a  class  of  maladies  which  Jacob 
Bigelow  in  1835  called  the  "self -limiting  diseases'*  ^  this 
innate  faculty  of  the  organism  to  overcome  infection  was 
recognized.  It  may  be  of  even  more  than  historical  in- 
terest to  reprint  here  the  pregnant  paragraph  in  which 
Bigelow  expresses  this  view : 

This  deficiency  of  the  healing  art  (he  is  now  writ- 
ing of  the  advances  in  knowledge  of  the  structure 
and  functions  of  the  human  body  in  contrast  to  the 
lagging  behind  of  the  science  of  therapeutics,  or  the 
branch  of  knowledge  by  the  application  of  which 
physicians  are  expected  to  remove  diseases)  is  not 
justly  attributable  to  any  want  of  sagacity  or  dili- 
gence on  the  part  of  the  medical  profession.  It  be- 
longs rather  to  the  inherent  difficulties  of  the  case 
and  is,  after  abating  the  effect  of  errors  and  acci- 
dents, to  be  ascribed  to  the  apparent  fact  that  certain 
morbid  processes  in  the  human  body  have  a  definite 
and  necessary  career,  from  which  they  are  not  to  be 
diverted  by  any  known  agents,  with  which  it  is  in 
our  power  to  oppose  them.  To  these  morbid  affec- 
tions, the  duration  of  which,  and  frequently  the  event 
also,  are  beyond  the  control  of  our  present  remedial 
means,  I  have,  on  the  present  occasion,  applied  the 
name  of  the  self -limited  diseases;  and  it  will  be  the 
object  of  this  discourse  to  endeavor  to  show  the  ex- 
^  Jacob  Bigelow,  Discourse  on  Self-limited  Diseases,  Boston, 
1835. 


130  CONTEMPORARY  SCIENCE 

istence  of  such  a  class,  and  to  inquire  how  far  certain 
individual  diseases  may  be  considered  as  belonging 
to  it. 

ANAPHYLAXIS 

Allusion  has  several  times  been  made  to  the  hyper- 
sensitive state  which  is  often  regarded  as  the  opposite  of 
the  immune  condition.  Because  the  latter  is  conceived  as 
protective  and  hence  is  spoken  of  as  being  prophylactic, 
the  former  in  turn  has  been  named  anaphylactic.  The 
obvious  distinction  between  the  two  conditions  is  simply 
defined  by  the  statement  that  while  the  immunized  animal 
shows  a  greater  degree  of  resistance  to  a  second  inocula- 
tion of  the  materials  used  for  immunization,  the  anaphy- 
lactized  animal  on  the  contrary  shows  a  heightened  sus- 
ceptibility. 

The  history  of  anaphylaxis  illustrates  the  manner  in 
which  the  rapidly  growing  knowledge  of  immunity  reacted 
on  the  appreciation  of  this  condition.  It  now  appears 
that  the  physiologist  Magendi,  who  flourished  in  the  first 
quarter  of  the  nineteenth  century,  first  noted  that  an 
animal  which  had  borne  without  apparent  effect  one  in- 
jection of  a  quite  harmless  protein  such  as  egg  white, 
reacted  severely  to  a  second  injection  of  the  same  kind  of 
material  given  after  an  interval  of  days.  No  further  con- 
temporary attention  seems  to  have  been  given  to  this  iso- 
lated incident,  and  it  was  not  until  1894  that  the  speaker 
chanced  again  upon  the  phenomenon.  He  was  engaged 
upon  a  study  of  the  pathologic  action  of  the  toxalbumins, 
and  his  attention  was  attracted  by  recent  experiments  on 
the  similar  globulicidal  (or  red  blood  corpuscle  destruc- 
tive) action  of  certain  alien  blood  serums,  such  for  ex- 
ample as  the  serum  of  the  dog  for  the  red  globules  of  the 
rabbit.  Since  animals  could  be  rendered  immune  to  the 
toxalbumins,  the  attempt  was  made  to  make  rabbits  im- 
mune to  dog's  serum,  but  without  success.  On  the  con- 
trary, it  was  found  that  animals  which  had  withstood  one 


TWENTY-FIVE  YEARS  OF  BACTERIOLOGY  131 

dose  of  dog's  serum  succumbed  to  a  second  dose  given 
after  the  lapse  of  some  days  or  weeks,  even  when  this 
dose  was  sublethal  for  a  control  animal. 

Again  the  observation  fell  on  stony  soil,  as  indeed  sub- 
sequent ones  were  destined  to  do  a  few  years  later  and,  as 
it  now  appears,  chiefly  because  knowledge  of  and  interest 
in  the  general  subject  of  immunity  had  not  progressed 
far  enough  at  that  period  to  present  to  the  contemplation 
of  the  "prepared  mind,''  to  use  Pasteur's  phrase,  the 
sharply  contrasted  hypersensitive  state. 

But  the  time  for  the  systematic  investigation  of  the 
phenomenon  was  approaching,  for  between  1902  and 
1904,  Richet  and  his  pupils  had  their  attention  arrested  by 
an  extraordinary  incident,  as  it  then  seemed.  In  under- 
taking  to  effect  immunization  with  certain  poisonous  pro- 
teins of  animals,  they  found  that  instead  of  inducing  re- 
sistance, they  induced  hypersensibility.  To  this  latter 
condition  they  applied  the  name  Anaphylaxis.  Although 
as  it  subsequently  turned  out,  the  idea  involved  miscon- 
ception of  the  nature  of  the  process,  yet  these  studies 
stand  forth  illuminatingly  as  recognizing  for  the  first  time 
the  dependence  of  the  hypersensitive  state  upon  a  pre- 
ceding injection  of  a  given  protein  substance  and  the 
necessity  of  an  incubation  period  covering  a  number  of 
days  between  the  injections,  in  order  that  the  sensitive 
condition  might  be  ushered  in.  That  the  sensitizing  ef- 
fect was  of  the  nature  of  a  general  biological  reaction  of 
the  animal  body  to  the  parental  introduction  of  natural 
proteins  into  the  body,  without  reference  to  their  primarily 
poisonous  character,  came  to  be  appreciated  a  little  later 
as  the  result  of  observations  made  on  rabbits  and  guinea, 
pigs  injected  and  then  reinjected  with  horse  serum,  as 
well  as  with  other  innocuous  proteins.  In  order  to  arouse 
the  reaction  of  immunity  in  the  animal  body,  some  degree 
of  primary  poisoning  of  the  cells,  as  with  bacteria,  their 
metabolic  products  and  similar  substances  originating  in 
other  varieties  of  living  beings,  must  be  accomplished; 


132  CONTEMPORARY  SCIENCE 

while  the  sensitive  state  arises  from  the  interaction  of  the 
animal  body  with  any  native  protein  substance  what- 
ever which  finds  its  way  directly  or  indirectly  into  the 
blood. 

From  the  many  investigations  which  now  ensued,  it 
appeared  that  while  many  kinds  of  warm-blooded  ani- 
mals are  subject  to  the  condition,  yet  the  most  striking, 
because  most  uniform  and  dramatic  effects  are  yielded 
by  the  guinea  pig,  which  has  since  become,  as  it  were,  the 
^'classical"  animal  for  observing  and  studying  anaphylaxis. 
The  reason  for  this  choice  arises  from  the  circumstance 
that  in  the  guinea  pig  a  sensitization  of  the  sm.ooth  muscle 
fibers  occurs,  so  that  in  reinjection  of  the  original  pro- 
tein, among  other  effects,  a  contraction  of  the  lining  mem- 
brane of  the  bronchi  takes  place,  which  by  closing  their 
lumiina  and  excluding  air,  quickly  causes  death  from 
asphyxiation.  Moreover,  the  guinea  pig  has  proved  ex- 
quisitely responsive  to  sensitization,  so  that  minute  quan- 
tities, measured  even  in  fractions  of  milligrams,  of  pure 
native  proteins  suffice  to  induce  a  specific  hypersensitive 
condition,  whence  it  has  followed  that  the  prepared  guinea 
pig  has  been  found  suitable  for  the  investigation  of  the 
ultimate  chemical  relationships,  not  otherwise  observable, 
which  subsist  between  native  proteins. 

Profoundly  different  as  are  the  obvious  features  of  the 
anaphylactic  and  immune  reactions,  yet  certain  of  the 
fundamental  conditions  governing  both  coincide.  It  will 
be  recalled  that  in  arousing  immunity  in  animals  by  arti- 
ficial means,  certain  new  substances  of  the  general  nature 
of  antipodes,  or  as  technically  named,  antibodies,  are 
made  to  arise  in  the  blood  of  the  treated  animal ;  and  it 
now  appears  that  in  the  course  of  sensitization  of  animals, 
antibodies  to  the  proteins  injected  also  develop.  In  both 
instances  the  material  originally  injected,  whether  pri- 
marily poisonous  or  not,  if  active,  belongs  to  a  class  now 
called  antigens,  that  is  generators  of  antibodies.  The  ex- 
pression of  the  immunity  reaction,  in  its  simplest  terms, 


TWENTY-FIVE  YEARS  OF  BACTERIOLOGY  133 

consists  of  a  chemical  or  physico-chemical  union  betweea 
the  original  antigen  and  the  manufactured  antibody,  tak- 
ing place  in  the  body  or  in  a  test  tube,  through  which  the 
primarily  poisonous  antigen  is  rendered  innocuous.  la 
other  words,  the  immune  antigen-antibody  complex  is  a 
harmless  compound. 

In  a  similar  manner  the  sensitizing  antigen  and  induced 
antibody  unite  in  anaphylaxis,  but  the  product  of  the  union 
is  essentially  different  from  the  one  just  considered,  ia 
that  it  is  highly  injurious,  and  the  effect  of  the  antigen- 
antibody  complex  is  not  to  protect,  but  to  poison  the  ani- 
mal. The  basic  distinction  between  the  immune  and  the 
anaphylactic  condition,  as  described,  is  further  enforced 
when  we  recall  that  the  original  toxic  protein  used  to 
immunize  is  detoxicated  in  the  course  of  the  immune  re- 
action and  the  original  non-toxic  protein  used  to  sensitize 
is  endowed  with  the  property  of  intense  toxicity  in  course 
of  the  latter  reaction. 

As  in  the  instance  of  the  immune  state,  a  still  undecided 
controversy  is  going  on  as  to  whether  the  hypersensitive 
condition  depends  upon  humoral  or  upon  cellular  factors. 
There  is  no  doubt  that  the  anaphylactic  antibody  exists 
free  in  the  blood,  and  hence  that  a  normal  animal  can  be 
rendered  passively  sensitive  by  the  infusion  of  blood  de- 
rived from  a  sensitized  animal.  It  is  equally  true  that 
the  anaphylactic  response  is  in  part  a  cellular  one,  as  in 
the  instance  mentioned  of  the  bronchial  musculature  stim- 
ulated to  contraction.  By  appropriate  experiments  it  can 
be  shown  that  organs  containing  smooth  muscle  taken 
from  sensitive  animals,  exhibit  the  equivalent  of  the 
anaphylactic  reaction  even  outside  the  living  body ;  and 
also  that  coincidentally  with  the  appearance  of  the 
"shock"  of  the  reaction  in  the  guinea  pig,  the  blood  be- 
comes incoagulable. 

Hypersensitiveness  may  exist  independently  of  pur- 
posive artificial  sensitization,  and  some  of  the  most  im- 
portant examples  of  that  condition  have  been  observed 


134  CONTEMPORARY  SCIENCE 

in  man.  Because  of  their  size,  perhaps  for  other  reasons, 
human  beings  even  when  sensitive  react  to  the  parenteral 
injection  of  native  proteins  less  severely  than  the  smaller 
animal  species.  And  yet  lamentable  instances,  if  very 
few  in  number,  of  serious  or  even  fatal  anaphlyactic  ef- 
fects have  been  observed  in  man.  These  have  occurred 
especially  in  connection  with  the  therapeutic  employment 
of  curative  serums  derived  from  the  horse.  The  greatest 
danger  from  this  source  is  at  the  time  of  the  first  injec- 
tion, for  while  severe  effects  do  sometimes  follow  upon 
a  second  or  subsequent  injection,  they  have  never  been 
attended  by  fatal  consequences.  Luckily,  means  are 
known  for  anticipating  these  even  infrequent  accidents, 
and  of  guarding  against  their  dangers  without  at  the  same 
time  depriving  those  in  need  of  the  benefits  of  serum 
protection  or  therapy. 

Beside  the  active  state  of  sensitization  another  is  known 
which  may  be  termed  negative.  Thus  it  has  been  found 
that  when  a  sensitive  animal  is  given  an  injection  of  a 
protein  which  produces  a  certain  degree  of  anaphylactic 
effect,  but  not  a  fatal  outburst,  the  treated  animal  can 
for  a  time  be  rendered  insensitive.  And  thus  human  be- 
ings who  are  sensitive,  say  to  horse  serum,  may  be  desen- 
sitized by  means  of  successive  small  inoculations  of  the 
diluted  serum,  and  while  in  the  refractory  state  thus  in- 
duced receive  without  risk  larger  injections  of  the  serum. 

On  the  other  hand,  lesser  states  of  anaphylaxis  in  man 
are  by  no  means  infrequent.  To  them  belong  the  rashes 
of  "serum  sickness"  following  the  injection  of  curative 
serums  which  while  annoying  are  not  dangerous,  and  the 
very  disagreeable  manifestations  of  hay  fever  and  its 
allied  conditions,  now  attributed  to  the  action  of  vege- 
table materials,  pollens  chiefly,  upon  the  sensitized  mu- 
cous membranes  of  the  nose  and  throat.  Recent  studies 
by  Auer  have  shown  that  animals  sensitized  with  harm- 
less proteins,  such  as  horse  serum,  develop  severe  local 
inflammations  when  from  any  local  cause  an  extrusion  of 


TWENTY-FIVE  YEARS  OF  BACTERIOLOGY  135 

the  antigen-containing  fluid  of  the  blood  is  enabled  to 
penetrate  the  extravascular  tissues;  and  on  the  basis  of 
this  observed  fact  he  has  suggested  that  functional  dis- 
turbances of  many  organs  of  the  body  in  sensitive  human 
subjects  may  be  brought  about  in  a  similar  manner. 

In  a  related  field  the  hypersensitive  reaction  has  been 
employed  to  aid  in  the  diagnosis  of  important  diseases  of 
man  and  animals.  It  is  apparent  from  what  has  been 
stated  of  the  site  of  the  fatal  anaphylactic  shock  in  the 
guinea  pig,  and  as  stated  a  moment  ago  of  the  sensitive- 
ness of  tissue  cells  in  general  to  the  circulating  anaphylac- 
tic antigen,  that  a  visible  local  reaction  might  be  obtainable 
by  introducing  the  protein  to  which  the  animal  or  person 
is  sensitive  into  a  visible  portion  of  the  body,  as  say  the 
skin.  In  this  way  sensitiveness  is  looked  for  before  serum 
injections  are  given,  tuberculin  is  employed  to  disclose 
hidden  foci  of  active  tuberculosis,  luetin  is  used  to  expose 
evidences  of  latent  syphilis,  and,  in  a  modified  manner, 
the  Schick  test  is  applied  to  determine  whether  exposed 
children  do  or  do  not  carry  in  their  blood,  spontaneously 
as  one  might  say,  sufficient  diphtheria  antitoxin  to  afford 
them  security  without  a  protective  serum  injection.  And 
beside  the  benefits  accruing  to  human  therapy  directly 
from  the  working  out  of  the  meaning  of  anaphylaxis  are 
to  be  placed  those  improvements  introduced  into  veteri- 
nary practice,  from  which  human  preventive  medicine 
also  has  derived  great  gain,  namely,  the  application  of  the 
tuberculin  test  in  clearing  milch  herds  of  actively  tuber- 
cular cattle,  and  of  mallein  to  the  controlling  of  glanders 
among  horses. 

FiLTERABLES 

As  we  move  from  the  contemplation  of  one  achieve- 
ment to  another  in  bacteriology,  we  rarely  pause  to  reflect 
how  far  circumstances  almost  accidental  have  favored 
the  gains.    The  working  out  of  the  biological  basis  of  fer- 


136  CONTEMPORARY  SCIENCE 

mentation  and  putrefaction,  and  a  little  later  of  the  mi- 
crobic  origin  of  disease,  is  obviously  bound  up  with  the 
perfection  of  the  compound  microscope,  and  the  useful- 
ness of  that  instrument  for  the  purpose  is  as  obviously 
bound  up  with  the  ultimate  size  of  bacteria  and  related 
organisms.  And  yet  without  the  fortunate  conjunction 
of  an  optical  device  and  the  degree  of  magnitude  of  liv- 
ing objects,  we  should  still  be  groping  in  outer  darkness 
in  the  search  for  the  origin  of  disease,  and  still  strug- 
gling with  the  phantoms  of  spontaneous  generation.  But 
the  great  men  who  proved  the  connection  between  micro- 
scopic life  and  the  biological  processes  mentioned,  in- 
cluding the  source  of  the  infectious  diseases,  did  more 
than  describe  the  phenomena  revealed  by  the  microscope 
and  otherwise.  They  established  methods  with  principles 
so  clearly  enunciated  and  rigidly  based  that  it  has  been 
found  possible  to  penetrate  into  an  inhabited  territory  in 
which  thus  far  the  most  powerful  microscope  has  not  al- 
ways enabled  us  to  discern  the  living  forms. 

Thanks  to  their  labors  we  know  now,  first,  that  the 
faculty  of  setting  up  disease  in  successive  individuals  is 
a  property  only  of  matter  which  can  itself  increase  indefi- 
nitely, and  all  matter  thus  constituted  is  possessed  of  life; 
and  second,  that  certain  disease-producing  parasites  can 
be  separated  mechanicall}^  from  the  soluble  products  of 
their  growth,  by  passage  through  earthenware  filters,  in 
which  the  interstices  or  pores  are  smaller  even  than  the 
size  of  the  microbes  themselves.  By  varying  the  density 
or  porosity  of  these  filters,  we  arrive  at  a  way  of  roughly 
estimating  the  size  of  the  microbic  cells. 

Thus  it  came  about  that  in  1898  two  German  bacteriolo- 
gists, Loeffier  and  Frosch,  who  were  engaged  on  the  study 
of  the  very  highly  communicable  foot  and  mouth  disease 
of  cattle,  discovered  that  after  diluting  the  contents  of 
the  unbroken  vesicles  which  arise  in  that  disease,  with  20 
to  40  times  their  volume  of  water  and  passing  them 
through   such   earthenware  filters,   the   filtrate   not   only 


TWENTY-FIVE  YEARS  OF  BACTERIOLOGY  137 

would  induce  the  disease  on  inoculation,  but  that  the  same 
series  of  events  followed  the  dilution  and  inoculation  of 
the  vesicular  contents  of  the  experimental  variety  of  dis- 
ease through  an  indefinite  series.  Obviously  the  filtrate 
contained  a  living  element  which  came  to  be  called  a 
virus,  just  as  is  the  small-pox  germ,  for  in  neither  instance, 
and  notwithstanding  laborious  endeavors,  has  the  living 
organism  itself  ever  been  seen  under  the  microscope. 

We  now  recognize  a  class  of  microbes  or  viruses  which 
are  so  minute  as  to  be  regarded  as  ultramicroscopic,  and 
yet  so  active  as  to  be  capable  of  setting  up  disease  in  ani- 
mals and  man.  The  precise  limits  of  the  class  have  yet 
to  be  defined.  When  we  consider  that  there  remain  still 
to  be  detected  the  microbic  incitants  of  some  of  the  most 
contagious  as  well  as  common  of  diseases,  our  minds  read- 
ily seize  hold  of  the  possibility  of  their  being  of  this  na- 
ture. Thus  the  microbes  responsible  for  such  contagious 
maladies  as  measles,  scarlet  fever,  and  chicken-pox,  and 
those  inducing  small-pox  and  rabies  are  not  known,  and 
not  a  little  obscurity  still  surrounds  the  etiology,  as  we 
say,  or  immediate  origin  of  epidemic  influenza. 

Inasmuch  as  the  filterable  microorganisms  or  viruses, 
or  filter  passers  as  the  British  prefer  to  call  them,  are 
known  alone  through  their  disease-producing  propensi- 
ties, no  one  can  say  whether,  as  is  true  of  the  bacteria, 
innumerable  kinds  exist  in  nature,  among  which  relatively 
a  small  number  has  acquired  parasitic  or  pathogenic  quali- 
ties. Of  the  less  than  a  dozen  diseases  known  or  on  good 
grounds  considered  to  be  induced  by  filterable  micro- 
organisms, two  attack  human  beings,  namely  poliomye- 
litis or  infantile  paralysis,  and  trench  fever ;  and  a  third, 
yellow  fever,  which  until  very  recently  was  believed  to  be- 
long also  in  this  category,  has  now  been  relegated  to 
another  class,  with  respect  to  which  special  devices  suffice 
to  bring  into  view  its  microbic  incitant. 

There  exists,  therefore,  a  degree  of  uncertainty  in  this 
field  of  research  for  which  allowance  must  be  made,  sincq 


138  CONTEMPORARY  SCIENCE 

it  may  well  happen  that  suddenly  through  a  fortunate 
series  of  experiments  or  the  opening  up  of  new  methods, 
a  parasite  hitherto  regarded  as  invisible  may  be  brought 
into  microscopic  view.  Should,  for  example,  complete 
evidence  be  brought  forward  to  relate  the  Rickettsia  bod- 
ies to  certain  specific  infectious  diseases  transmitted 
especially  by  insects,  as  by  the  wood  tick  in  Rocky  Moun- 
tain spotted  fever,  and  lice  in  trench  and  typhus  fever, 
then  another  group  will  have  been  transferred  from  among 
the  ultramicroscopic  to  the  visible  parasites.  A  similar 
situation  exists  regarding  the  globoid  bodies  of  poliomye- 
litis, the  disease  of  man  most  convincingly  established  as 
induced  by  a  filterable  microorganism.  By  means  of  a 
highly  specialized  method  of  cultivation  applicable  espe- 
cially to  the  class  of  spiral  microbes,  or  spirochetse.  Dr. 
Noguchi  and  the  speaker  isolated  from  the  nervous  or- 
gans of  cases  of  poliomylitis,  globular  bodies  so  minute 
as  to  be  just  at  the  limit  of  visibility  under  the  highest 
power  of  the  microscope.  With  cultures  of  these  bodies 
they  induced  experimental  poliomyelitis  in  the  monkey; 
but  the  culture  method  itself  is  so  intricate  that  thus  far 
few  bacteriologists  have  been  able  to  repeat  the  work, 
which,  therefore,  still  awaits  final  confirmation. 

Since  the  recent  pandemic  of  influenza  and  the  assault 
made  upon  the  so-called  influenza  bacillus  of  PfeifiFer, 
isolated  first  in  Germany  during  the  influenza  epidemic 
of  1889-1890,  the  inciting  microbe  of  that  disease  has 
been  sought  among  the  filterables.  The  announcement  of 
the  finding  of  such  a  parasite  in  the  nasopharyngeal  se- 
cretions by  Nicolle  and  Lebailly  of  Paris  in  the  autumn 
of  1918,  aroused  high  hopes  which  subsequent  investiga- 
tions have  not  served  to  sustain.  The  problem  was  ap- 
proached in  a  somewhat  different  manner  by  two  workers 
— Olitsky  and  Gates,  at  the  Rockefeller  Institute.  Their 
studies  embraced  two  periods,  the  epidemics  of  1918-1919 
and  1920,  and  the  intervening  (interepidemic)  period, 
the  latter  serving  as  a  control  for  the  former.     The  es- 


TWENTY-FIVE  YEARS  OF  BACTERIOLOGY  139 

sence  of  their  investigations  consisted  in  injecting  through 
the  trachea  into  the  lungs  of  rabbits  saline  nasopharyngeal 
washings  derived  within  the  first  24  to  36  hours  after  the 
appearance  of  symptoms  from  influenza  patients  and  ob- 
serving the  effects  (a)  upon  the  blood  and  (b)  upon  the 
lungs.  The  striking  changes,  in  the  successful  experi- 
ments, relate  to  the  white  corpuscles  of  the  circulating 
blood  which  suffer  a  numerical  depression  affecting  chiefly 
the  mononuclear  type  of  cells,  and  to  the  lungs  in  which 
multiple  hemorrhages  and  edema,  but  not  pneumonia, 
arise.  The  effects  are  correlated :  where  no  lung  lesions 
are  found  no  blood  alterations  occur.  These  objective 
phenomena  are  induced  by  filtered  materials  free  of  all 
ordinary  bacteria  (aerobic  and  anaerobic)  and  they  have 
not  been  secured  otherwise  than  with  materials  derived 
from  early  cases  of  epidemic  influenza ;  but  when  present, 
the  rabbits  affected  very  readily  become  subject  to  the 
action  of  various  other  bacteria  (streptococci,  pneumo- 
cocci,  staphylococci,  influenza  bacilli),  to  which  they  are 
otherwise  resistant,  but  which  then  settle  in  the  lungs  and 
excite  fatal  pneumonic  affections.  The  unassisted  action 
of  the  influenzal  material  is  not  fatal ;  only  when  an  ordi- 
nary bacterial  lung  infection  is  superadded  does  death 
follow.  All  who  are  familiar  with  the  effects  in  man  of 
pure  influenza  and  then  of  influenza  complicated  with 
pneumonia  of  pneumococcal,  streptococcal,  etc.,  origin 
will  appreciate  this  distinction. 

What  also  characterizes  the  class  of  diseases  incited  by 
the  true  filterable  parasites  in  their  high  degree  of  speci- 
ficity and  the  enduring  immunity  which  follows  recovery 
from  an  attack.  This  is  true  among  animals,  for  instance, 
of  hog  cholera  and  foot  and  mouth  disease,  and  in  man 
of  poliomyelitis.  This  specificity  is  shown  by  the  difficulty 
or  impossibility  of  implanting  the  virus  on  specifically  re- 
mote animals.  In  poHomyelitis,  for  example,  only  mon- 
keys are  subject  to  experimental  infection,  in  hog  cholera 
and  foot  and  mouth  disease,  only  swine  and  cattle.    Bear- 


I40  CONTEMPORARY  SCIENCE 

ing  in  mind  Behring's  dictum  that  to  produce  a  thera- 
peutic serum,  it  is  essential  to  immunize  highly  susceptible 
animals,  it  becomes  evident  why  success  has  not  crowned 
the  many  undertakings  to  prepare  an  antipoliomyelitis 
serum  in  the  horse  or  other  large  animal,  and  why  it  is 
only  by  the  use  of  swine  themselves  that  an  anti-hog- 
cholera  serum  has  been  secured. 

The  investigation  of  this  class  of  excessively  minute  or 
filterable  parasites  casts  a  sharp  ray  of  light  into  a  neigh- 
boring field  of  biological  research  which  at  the  time 
aroused  hopes  of  further  rapid  progress  but  which  the 
intervening  time  and  effort  have  not  realized. 

Perhaps  no  subject  in  experimental  pathology  has  been 
pursued  with  more  thought  and  energy  than  the  one  to 
which  the  name  of  cancer  research  is  applied.  The  rea- 
sons are  obvious.  The  nature  of  the  source  of  the  can- 
cerous tumors  is  still  shrouded  in  essential  darkness.  It 
is,  of  course,  known  that  cancer  sometimes  follows  upon 
prolonged  irritation  and  inflammation  of  tissues  variously 
excited.  But  what  the  immediate  impulse  is  that  calls 
forth  the  cancerous  state  is  unknown.  And  yet  advances 
have  come  from  the  study  of  the  spontaneous  and  trans- 
plantable cancers  in  mice,  rats  and  some  other  animals.  A 
long  series  of  biological  conditions  governing  the  growth 
and  recession  of  the  tumors  have  been  uncovered,  and  by 
altering  those  conditions,  on  the  one  hand  growth  can 
be  promoted,  and  on  the  other,  retarded.  In  this  way, 
Murphy  and  his  co-workers  have  accounted  for  the  in- 
fluence of  the  action  of  the  X-ray  in  affecting  cancer 
growth;  and  by  observing  the  correlative  effects  on  the 
lymphoid  structures  of  the  body,  which  are  very  sensitive 
to  the  rays,  and  the  changes  corresponding  to  them  in  the 
circulating  blood,  they  have  so  altered  the  scale  as  almost 
at  will  either  to  aboTish  or  stimulate  the  development  of 
mouse  cancers. 

But  these  experimental  results  and  others  of  a  class  in 
which  the  defensive  forces  of  the  body  can  be  marshalled 


TWENTY-FIVE  YEARS  OF  BACTERIOLOGY  141 

against  the  implanted  cancer  cells,  throw  no  real  light 
upon  the  series  of  events  underlying  the  origin  of  cancer. 
The  light  referred  to  was  shed  by  the  studies  of  Rous,  of 
the  Rockefeller  Institute,  upon  a  sarcoma,  or  fleshy  can- 
cer, of  the  domestic  fowl.  This  cancer,  which  arises  at 
times  spontaneously  in  fowl,  is  subject  to  successful  im- 
plantation in  other  fowl.  The  specificity  is  accurate;  it 
will  not  grow  in  other  birds  and  grows  best  in  the  variety 
of  fowl  in  an  individual  of  which  it  originally  appeared. 
Its  growth  is  first  local,  as  is  cancer  in  man,  and  later 
metastatic,  or,  appearing  at  a  distance  and  starting  from 
microscopic  masses  of  cells  derived  from  the  original 
tumor  and  carried  by  the  circulation  to  remote  parts  of 
the  body.  The  altogether  new  and  unprecedented  fact 
about  this  tumor,  which  has,  however,  not  yet  been  found 
to  be  true  of  the  cancers  of  mammals,  is  that  it  may  be 
induced  by  the  injection  into  the  susceptible  variety  of 
fowls,  of  a  cell-free  filtered  extract  of  the  tumor.  In 
other  words,  Rous  has  accomplished  for  this  tumor  what 
bacteriologists  had  effected  for  a  certain  refractory  group 
of  the  infectious  and  communicable  diseases,  namely,  re- 
lating it  to  a  form  of  life  not  imagined  by  the  founders 
of  bacteriology,  but  which  their  discoveries  in  the  field  of 
the  living  microscopic,  as  opposed  to  the  ultramicroscopic, 
universe  brought  within  range  of  recent  biological  re- 
search. 

SPIROCHETES 

The  vicissitudes  of  bacteriological  science,  like  those  of 
other  sciences,  have  depended  upon  time  and  method,  and 
sometimes  the  one  and  sometimes  the  other  has  served  to 
promote  discovery.  When  by  a  happy  conjunction  of 
circumstances,  time  and  method  happen  to  conjoin,  then 
advances  almost  startling  in  nature  may  take  place. 

It  is  in  this  way  that  we  may  view  the  remarkable  prog- 
ress of  events  in  connection  with  a  class  of  special  micro--: 


142  CONTEMPORARY  SCIENCE 

organisms  or  spirochetae,  so  called  since  Schaudinn's  dis- 
covery in  1905  of  the  pallida,  the  microbic  inciter  of 
syphilis.  The  search  for  the  microbe  of  syphilis  had  been 
unremitting-  since  the  early  days  of  bacteriology,  and  not 
a  few  false  claimants  held  the  field  for  a  brief  space. 
Schaudinn's  discovery  was  very  soon  confirmed,  and  has 
now  been  firmly  established ;  and  it  is  interesting  to  note 
that  in  fact  it  was  itself  a  confirmation  of  an  observation 
made  a  few  years  earlier  by  Metchnikoff  and  Bordet,  who, 
however,  because  of  the  technical  difficulties  of  the  quest 
did  not  succeed  in  confirming  their  own  findings.  The 
unusual  difficulties  surrounding  the  detection  of  the  liv- 
ing pallida  in  the  body  fluids,  because  of  its  extreme  ten- 
uity merely  heighten  the  respect  we  must  hold  for  the 
zoologist  Schaudinn's  perspicacity.  Very  soon  staining 
methods  were  introduced  to  lighten  the  task  of  detecting 
the  pallida,  but  so  capriciously  did  they  act  and  so  baffling 
did  the  ordinary  microscopic  detection  prove,  that  the 
great  promise  of  the  employment  of  the  pallida  for  pur- 
poses of  diagnosis  and  treatment  was  not  at  once 
realized. 

None  the  less,  a  great  advance  in  bacteriology  had  been 
achieved,  and  a  new  class  of  microbes  potentially  disease- 
producing  was  presented  for  study.  Within  a  year  a 
second  spirochete,  called  pertenuis,  was  discovered  in  the 
lesions  of  yaws,  a  tropical  disease  having  certain  affinities 
with  syphilis.  The  search  for  the  delicate  spiral  organisms 
was  not  an  easy  one,  and  only  the  masters  of  bacteriologi- 
cal technique  were  likely  to  succeed  in  it.  Then  suddenly 
the  labor  was  lightened  and  the  road  made  smooth  for  a 
rapidly  succeeding  succession  of  discoveries  in  this  field 
by  the  invention  and  application  of  the  dark-field  or  ultra- 
microscope.  This  instrument  was  perfected  for  observing 
you  are  aware,  operates  by  projecting  powerful  rays  of 
light  in  directions  parallel  to  the  surface  of  the  micro- 
scopic slide.  Such  a  field  if  optically  empty  will  be  dark 
and  not  luminous ;  but  if  particles  are  present  in  it,  the 


TWENTY-FIVE  YEARS  OF  BACTERIOLOGY  143 

rays  of  light  will  be  intercepted  and  the  particles  illumi- 
nated. They  in  turn,  and  according  to  their  size,  will 
appear  as  bright  objects,  or  when  very  small,  give  a  dif- 
fuse luminosity  to  the  field.  The  phenomenon  is  similar 
to  the  one  described  by  Tyndall,  in  which  a  beam  of  light 
passed  through  a  dark  space  containing  suspended  par- 
ticles causes  them  to  become  visible.  When  the  suspended 
matter  consists  not  only  of  dispersed  particles,  but  of  mi- 
croorganisms, these  also  become  luminous,  and  when,  as 
with  the  spirochete,  they  exhibit  a  wavy  structure  and  in- 
dependent motion,  they  at  once  arrest  attention.  To-day 
the  dark-field  microscope  is  found  in  every  well-equipped 
clinic,  and  it  has  aided  in  adding  many  new  species  to  the 
already  considerable  number  of  microbes  known  to  be  dis- 
ease-producing. 

The  latest  significant  addition  to  this  field  is  the  Lep- 
tospira icteroides,  or  the  jaundice-producing  spiral,  which 
Noguchi  has  recently  detected  in  the  blood  and  internal 
organs  of  cases  of  yellow  fever.  His  extensive  investi- 
gations carried  on  in  Ecuador,  Mexico,  and  Peru,  as  well 
as  at  the  Rockefeller  Institute,  have  rendered  it  highly 
probable  that  this  spirochete  is  the  microbic  incitant  of 
that  severe  epidemic  disease. 

Yellow  fever,  as  you  know,  is  an  insect-borne  disease 
and  arises  from  the  insertion  into  the  blood  of  man  of  a 
virus  carried  by  a  particular  mosquito — Stegomyia  calo- 
pus.  After  the  mosquito  transporting  the  virus  has  bitten 
a  healthy  person,  an  interval  of  about  five  days  elapses 
before  his  blood  becomes  infective,  and  the  infectiousness 
endures  about  three  days  longer.  During  the  latter  pe- 
riod the  blood  serum  can  be  passed  through  the  finest- 
grained  porcelain  filters  without  losing  its  infectivity.  On 
the  other  hand,  a  normal  mosquito  which  has  bitten  a 
yellow  fever  patient,  does  not  become  capable  of  infect- 
ing other  human  beings  until  after  about  twelve  days. 
Hence  the  insect  acts  not  merely  passively,  as  a  needle 
might,  as  the  conveyer  of  the  virus,  but  it  is  necessary 


144  CONTEMPORARY  SCIENCE 

in  order  to  increase  or  otherwise  modify  the  infective 
material  withdrawn  from  the  blood. 

The  discovery  of  the  yellow  fever  spiral  definitely  re- 
moves the  disease  from  the  class  believed  to  be  provoked 
by  ultramicroscopic  organisms,  and  at  the  same  time  adds 
so  well  defined  a  microbe  as  Leptospira  icteroides  to  the 
group  of  filter  passers.  The  data  so  far  secured  regard- 
ing this  spiral  in  relation  to  yellow  fever  fulfill  the  con- 
ditions arising  out  of  Reed  and  Carroll's  discoveries  in 
connection  with  the  disease  in  man.  These  are  great  gains 
for  theoretical  bacteriology.  The  rewards  to  practical 
medicine  are  even  greater,  since  it  has  been  found  that 
Leptospira  icteroides  lends  itself  to  the  making  of  an 
active  vaccine  (killed  organisms)  and  also  an  eflfective 
therapeutic  serum.  Hereafter  yellow  fever  is  to  be  com- 
bated (i)  by  removing  the  breeding  places  of  the  stego- 
myia,  (2)  through  vaccination,  and  (3)  by  an  antiserum. 

The  etiology,  or  causation,  of  yellow  fever  so  long  and 
fruitlessly  sought  seems  to  have  been  solved,  and  it  may 
be  of  interest  to  inquire  why  just  at  this  juncture?  The 
answer  is,  through  the  conjunction  of  the  "prepared  mind" 
and  animal  experimentation.  For  nearly  a  decade  No- 
guchi  has  been  investigating  this  spiral  class  of  microbes, 
in  course  of  which  he  added  materially  to  our  knowledge 
of  methods  of  study  and  of  new  species.  He  had  first- 
hand knowledge  of  a  related  disease,  infectious  jaundice, 
transmissible  to  guinea  pigs,  which  prevails  endemically 
in  Japan  and  sporadically  elsewhere,  and  in  which  Inada 
had  discovered  a  peculiar  spiral  organism  (Spirocheta 
ichterohcomorrhagioe) ,  In  other  words,  the  time  was  ripe 
and  Noguchi  peculiarly  equipped  to  take  up  again  and  in- 
vestigate with  newer  methods  the  problem  of  yellow 
fever. 

The  story  is  still  incomplete,  as  recent  developments 
have  shown ;  for  just  as  Metchnikoif  and  Bordet  had  seen 
the  pallida  before  Schaudinn,  so  it  now  appears  Stimson 
of  the  U.  S.  Public  Health  Service  had  previously  ob- 


TWENTY-FIVE  YEARS  OF  BACTERIOLOGY  14S 

served  the  icferoides.  He  examined  a  series  of  sections 
of  organs  stained  by  Levaditi*s  method  to  show  spiral 
organisms,  taken  from  a  patient  having  yellow  fever  who 
succumbed  in  New  Orleans  in  1907,  and  in  the  kidney 
found  spiral  forms  to  which  he  gave  the  name  of  Spiro- 
cheta  interrogans,  but  the  significance  of  which  could  not 
then  be  determined,  and  which  Noguchi  now  identifies  as 
the  icteroides.  Coming  at  this  time  and  in  this  way,  the 
observation  is  a  welcome  confirmation.  Without  the  many 
data  since  supplied  by  Noguchi's  experiments  and  studies 
of  living  cases  of  yellow  fever,  it  possesses  only  sug- 
gestive value.  The  finding  came  too  early  in  the  develop- 
ment of  our  knowledge  of  the  spirochete,  and  again  the 
seed  fell  on  stony  ground. 

There  remains  one  further  aspect  of  this  incomplete 
discussion  of  spiral  microbes  in  their  relation  to  disease 
to  be  considered  briefly,  namely  their  separation  into  two 
classes  according  as  the  diseases  induced  by  them  re- 
spond to  treatment  on  the  one  hand  by  curative  serums, 
and  on  the  other  by  so-called  drugs  or  chemicals.  It  has 
just  been  stated  that  yellow  fever  can  be  combated  by 
a  serum  of  this  kind,  and  the  same  is  true  of  infectious 
jaundice.  In  this  respect  the  two  inciting  microbes — L. 
icteroides  and  S,  ictero-hoemorrhagioe — ^behave  as  do  cer- 
tain bacteria.  But  the  spirochete  of  syphilis  and  yaws 
and  some  others  are  not  subject  to  serum  influences,  and 
hence  they  and  the  disease  they  induce  must  be  attacked 
from  another  quarter,  and  in  this  instance  with  chemicals 
for  which  they  evince  an  extraordinary  selectiveness,  as 
do  the  malarial  organisms  and  certain  parasitic  trypano- 
somes  which  are  of  protozoal  nature. 

CHEMOTHERAPY 

Chemotherapy  is  the  name  applied  to  the  branch  of  ex- 
perimental medicine  in  which  chemicals,  or  drugs,  are 
searched  for,  and  when  necessary  and  possible,  fashioned 


146  CONTEMPORARY  SCIENCE 

to  subdue  a  particular  kind  or  class  of  infection.  The 
beginnings  of  chemotherapy  reach  into  the  dim  past ;  the 
science  of  chemotherapy  is  just  being  built  up.  The 
epochal  discoveries  of  the  curative  value  of  cinchona  bark 
in  malaria  and  of  mercury  in  syphilis,  are  examples  of  the 
early,  and  as  we  now  say  empirical  working  out  of  speci- 
fic therapeutics.  But  in  emphasizing  these  two  triumphs 
of  the  empiric  period  long  antedating  the  experimental 
epoch  in  medicine,  sight  should  not  be  lost  of  the  essen- 
tial point,  namely  that  the  virtues  of  those  remedies  were 
established  also  by  experiment  carried  out  over  long  dec- 
ades and  upon  man  himself,  for  in  no  other  way  could 
these  active  drugs  have  been  separated  from  the  thousands 
of  innocuous  or  even  harmful  ones  applied  by  man  at  all 
stages  of  his  evolution  to  the  alleviation  of  suffering. 

In  a  strict  sense,  curative  serums  are  examples  of 
chemotherapy,  and  the  most  specific  ones  known,  since 
they  are  so  exactly  adapted  to  combat  a  given  microbe  or 
its  toxin,  and  because  in  the  end  the  active  component  is 
chemical  in  character.  But  as  usually  employed,  the  term 
is  applied  rather  to  chemicals  or  drugs  not  produced  by 
the  animal  body  and  of  definite  and  ascertainable  ultimate 
composition. 

The  beginnings  of  the  experimental  science  of  chemo- 
therapy are  very  recent,  and  hardly  more  than  a  start  has 
been  made  in  exploring  the  field.  The  principle  on  which 
it  is  based  can  be  expressed  simply :  microbic  parasites  on 
invading  the  animal  body  arouse  defensive  activities  on 
the  part  of  the  host,  which  when  of  sufficient  intensity 
serve  to  weaken  and  restrain,  and  ultimately  to  overthrow 
and  conquer  the  invaders.  These  natural  defenders,  as 
we  learned  earlier,  consist  of  fluid  and  cellular  consti- 
tuents of  the  body,  sometimes  performed,  sometimes  only 
manufactured  on  demand,  and  in  part  especially  adapted 
to  the  particular  parasitic  agent  to  be  vanquished. 

With  this  picture  before  them,  of  the  manner  of  the 
body's  defense  against  microbic  invasion,  bacteriologists 


TWENTY-FIVE  YEARS  OF  BACTERIOLOGY  147 

could  appreciate  that  the  overcoming  and  healing  of  in- 
fection is  never  a  mere  passive  process,  and  the  action  of 
healing  agents  in  the  body  does  not  occur,  as  the  older 
therapeutics  believed,  precisely  as  would  happen  if  the 
parasitic  agent  could  be  exposed  to  the  effects  of  drugs, 
say  in  a  test  tube.  Moreover,  it  was  always  evident  that 
such  effective  drugs  as  quinine  and  mercury  must  be  em- 
ployed sparingly,  because  while  they  were  able  to  injure 
and  thus  to  lead  to  the  destruction  of  the  microbes  in- 
ducing malaria  and  syphilis,  they  were  likewise  capable 
of  injuring  the  component  cells  of  the  body  itself. 

The  outstanding  instance  in  which  experimental  chemo- 
therapy has  registered  a  great  success  is  in  connection  with 
the  organic  compounds  of  arsenic,  which  have  been 
adapted  to  the  overcoming  of  infection  induced  on  the 
one  hand  by  spirochetes  and  on  the  other  by  trypanosomes. 
That  arsenical  compounds  possess  therapeutically  active 
properties  against  these  two  classes  of  parasitic  diseases 
— as  represented  on  the  one  hand  by  syphilis  and  on  the 
other  by  African  sleeping  sickness — is  not  entirely  a  re- 
cent discovery;  but  until  the  systematic  investigations  of 
Ehrlich  were  instituted,  which  ultimately  yielded  salvar- 
san,  knowledge  was  fragmentary,  medical  practice  based 
on  it  ineffective,  and  the  road  to  progress  obscure.  Now 
the  outlook  is  wholly  changed,  and  there  is  going  forward 
an  active  and  either  already  successful  or  at  least  highly 
promising  search  for  new  drugs  or  chemicals,  directed 
against  both  the  bacterial  and  the  protozoal  parasitic  mi- 
crobes. This  territory  so  newly  opened  to  exploration  in 
which  organic  chemists  and  pathologists  should  pool  inter- 
ests in  order  to  move  forward,  is  of  almost  infinite 
possibility,  since  the  number  of  chemicals  is  nearly  limit- 
less which  can  be  produced  and  so  fashioned  as  to  injure 
and  subdue  as  it  were  the  parasitic  invader,  and  at  the 
same  time,  pass  over  and  leave  little  influenced  the  ad- 
jacent body  cells.  But  the  conditions  of  the  search  are 
intricate  since,  as  just  indicated,  a  useful  drug  must 


148  CONTEMPORARY  SCIENCE 

exhibit  high  power  of  attack  upon  the  protoplasm  of  a 
parasitic  microbe  and  a  low  one  on  that  of  the  cells  of  the 
blood  and  the  organs,  in  order  that  the  former  and  not  the 
latter  may  be  predominately  affected.  It  is  a  peculiarity 
of  chemicals  as  contrasted  with  serums  that  they  can 
never  be  so  accurately  designed  to  their  purposes  as  to 
remain  entirely  without  effect  on  the  cells  of  the  host ;  but 
it  is  also  recognized  that  when  the  drugs  are  effective, 
they  do  not  carry  on  a  single-handed  combat,  but  serve 
best  when  they  either  assist  or  are  assisted  by  the  natural 
defensive  mechanisms  of  the  body,  which  also  are  roused 
into  action  to  overpower  the  invader  and  the  cooperation 
of  which  often  insures  protection  against  reinvasion,  ac- 
quired at  the  end  of,  and  in  consequence  of,  the  struggle. 

INFECTION   AND   SURVIVAL 

Infection  and  the  mastering  of  infection  are  intricate 
biological  processes  in  which  contending  forces  are 
brought  into  play  one  against  the  other,  whence  a  strug- 
gle ensues.  We  have  seen  that  the  host  stands  ready 
equipped  with  mechanisms  of  defense  which  may  be 
quickly  mobilized,  and  which  undergo  favorable  modifica- 
tion during  infection,  when  as  we  say,  it  proceeds  toward 
a  favorable  termination.  The  bacteriologist  has  learned 
within  the  past  quarter  of  a  century  to  imitate  nature's 
method  of  surmounting  infection  by  supplying  certain  of 
the  defensive  implements  artificially  wrought  to  be  brought 
to  her  aid  in  time  of  stress  and  need,  and  the  chemist  is 
learning  more  and  more  the  manner  of  adapting  drugs  to 
the  destruction  of  the  microbic  parasites  of  disease  for  a 
like  purpose. 

All  the  advantage  is,  however,  not  on  the  side  of  the 
body,  since  the  parasites  also  possess  powers  of  modifica- 
tion, through  which  the  most  elaborate  obstacles  placed  in 
their  way  by  the  host  may  be  rendered  futile. 

These  adaptations  consist  in  the  acquisition  of  special 


TWENTY-FIVE  YEARS  OF  BACTERIOLOGY  149 

properties  of  aggressive  action  or  virulence,  with  which 
is  associated  the  abiHty  to  produce  and  Hberate  substances 
paralyzing  to  the  defensive  processes  of  the  host.  Again, 
the  parasites  may  surround  themselves  with  a  kind  of 
mantle,  protecting  them  from  the  potentially  destructive 
effects  of  serum  and  phagocyte.  Or  they  may  undergo  an 
internal  change  of  constitution,  through  which  resistance 
to  injurious  agencies  not  normal  to  the  species  is  de- 
veloped. The  last  condition  is  called  "fastness"  and  has 
been  observed  especially  among  trypanosomes  and  spiro- 
chetes exposed  within  the  body  of  the  host  to  ineffective 
amounts  of  specific  serums  or  chemicals.  * 

With  so  many  factors  interplaying,  it  is  not  difficult  to 
perceive  that  the  problem  of  infection  is  a  complex  one, 
both  as  regards  its  occurrence  and  its  issue.  But  our 
understanding  of  the  conditions  under  which  it  arises  has 
been  immeasurably  extended  by  the  discovery  of  the  in- 
sect and  higher  animal  agencies  in  communicating  infec- 
tive agents  to  man,  and  of  the  part  played  by  so-called 
microbe  carriers,  those  unfortunate  and  innocent  persons 
who  have  recovered  from  or  merely  been  exposed  to  a 
communicable  disease,  or  suffered  a  slight,  abortive,  or 
ambulant  attack  of  which  they  are  ignorant,  and  the  dis- 
covery of  the  usual  portals  of  entry  into  the  body  of 
pathogenic  microorganisms. 

Infectious  diseases  prevail  in  two  more  or  less  distinct, 
but  at  times  interwoven  ways,  which  we  speak  of  as  the 
sporadic  and  the  epidemic.  The  former  represents  the 
ordinary  manner  of  spread,  the  latter  the  occasional  or 
periodic  explosive  outbreak  or  wave,  such  as  has  been 
experienced  recently  with  the  pandemics  of  poliomyelitis, 
influenza  and  lethargic  encephalitis. 

What  has  been  sought  in  the  past  and  is  being  assidu- 
ously looked  for  in  the  present  is  an  adequate  explanation 
of  the  transition  from  the  sporadic  to  the  epidemic  type 
of  disease.  We  possess  already  quite  accurate  numerical 
data  which  show  the  manner  in  which  epidemics  begin. 


150  CONTEMPORARY  SCIENCE 

how  they  reach  their  maximum  or  peak,  and  then  how 
they  fall  away  again.  Indeed,  we  now  construct  easily 
and  recognize  readily  the  epidemic  curves  of  different 
epidemic  diseases.  But  it  is  to  be  hoped  that  a  new  era 
is  appearing  in  the  study  of  epidemiology  in  which  experi- 
ment may  play  a  part  along  with  observation,  statistical 
and  other.  Already  beginnings  are  being  made  in  the  at- 
tempt to  define  the  distinction  between  the  potentially 
fluctuating  grades  or  power  of  infectivity  and  degree  of 
virulence,  taking  the  former  to  mean  the  natural  propen- 
sity which  a  microbe  displays  in  penetrating  the  ordinary 
portals  leading  into  the  body  and  its  ability  to  survive  and 
multiply  there,  and  the  latter  the  capacity  to  overcome  the 
natural  defenses  when  artificially  inoculated.  This  is  a 
field  clearly  approachable  by  experiment,  using  small 
laboratory  animals,  among  which  arise  from  time  to  time, 
and  much  as  happens  with  man  himself,  destructive  epi- 
demics induced  by  known  microbes.  Finally,  there  is  the 
field  in  which  not  a  single  species  of  microbe  is  concerned 
but  more  than  one,  the  first  preparing,  the  other  utilizing 
the  prepared  way  for  its  more  vicious  purposes.  Fre- 
quent examples  of  the  last  condition  are  observed  among 
the  lower  animals,  in  which,  of  course,  the  opportunities 
for  study  are  superior  to  those  existing  in  man;  but  re- 
cent experiences  in  this  and  other  countries  during  the 
influenza  epidemic  carry  conviction  of  this  relationship, 
since  the  original  disease  is  recognized  to  be  not  of  severe 
nature,  while  the  pneumonia  engrafted  upon  it  is  admit- 
tedly of  highly  fatal  character. 

My  purpose  in  reviewing  some  of  the  notable  events 
and  tendencies  in  bacteriology  which  have  come  to  light 
in  the  past  twenty-five  years  has  been  to  present  to  your 
consideration  the  achievements  in  one  branch  of  modern 
medicine,  and  to  indicate  the  relation  subsisting  between 
medicine  and  the  more  fundamental  sciences  of  physics, 
chemistry  and  biology.     Bacteriology  has  depended  also 


TWENTY-FIVE  YEARS  OF  BACTERIOLOGY  151 

for  its  development  on  its  sister  sciences  of  physiology, 
pharmacology  and  pathology,  without  which  many  of  its 
phenomena  could  not  be  interpreted.  It  seems  but  proper 
to  state  that  what  has  been  attempted  here  for  bacteriology 
could  readily  be  equalled  or  even  exceeded  by  spokesmen 
for  those  sister  sciences,  so  surely  has  medicine  grown 
scientific  in  recent  times. 


BEFORE  AND  AFTER  LISTER 

(Two  lectures  before  the  U.  S.  Army  Medical 
School,  Washington,  D.  C,  April  27  and  28, 
1915) 

BY 

W.  W.  Keen 

Emeritus  Professor  of  Surgery 

Jefferson  Medical  College, 

Philadelphia 

LECTURE   I.      "before    LISTER*' 

On  July  I,  1861,  I  entered  the  service  of  the  State  of 
Massachusetts  as  assistant  surgeon  of  the  Fifth  Massa- 
chusetts, and  on  July  4  was  sworn  into  the  service  of  the 
United  States  in  the  shadow  of  yonder  capitol.  On 
August  I  I  was  honorably  discharged  and  resumed  my 
medical  studies  at  the  Jefferson  Medical  College.  Strange 
as  it  now  seems,  when  assistant  surgeon  I  was  not  yet  a 
graduate  in  medicine.  As  an  evidence  of  the  loose  way 
in  which  medical  and  military  matters  were  then  con- 
ducted, I  was  actually  appointed  without  any  examination 
whatever. 

After  graduating  in  March,  1862,  I  again  entered  the 
service  in  May,  after  an  examination,  and  was  ordered  to 
the  Eckington  Hospital  in  the  then  outskirts  of  Washing- 
ton. Shortly  afterwards  I  was  ordered  to  fit  up  two 
churches  as  hospitals  and  to  have  them  ready  in  five  days. 
It  was  5  P.M.  on  a  Saturday  afternoon. 

152 


BEFORE  AND  AFTER  LISTER  153 

People  sometimes  imagine  that  a  practising  physi- 
cian can  be  transformed  into  an  army  surgeon  merely 
by  putting  a  uniform  on  him.  I  was  not  lacking  in 
ordinary  intelligence  and  was  willing  to  work,  but  I 
was  utterly  without  training.  To  get  those  two 
churches  ready  as  hospitals  I  had  to  have  beds,  mat- 
tresses, sheets,  pillow-cases,  chairs,  tables,  kitchen 
utensils,  knives,  forks,  spoons,  peppers  and  salts,  all 
sorts  of  crockery  and  other  necessities  for  a  dining- 
room,  all  the  drugs,  appliances  and  instruments 
needed  for  two  hundred  sick  and  wounded  men;  I 
needed  orderlies,  cooks  and  the  endless  odds  and  ends 
of  things  which  go  to  make  up  a  well-organized  hos- 
pital. I  did  not  know  how  to  get  a  single  one  of 
these  requisites.  As  to  drugs,  I  did  not  know  whether 
to  order  six  ounces  or  a  gallon  of  laudanum,  an 
ounce  or  two  or  a  pound  or  two  of  opium,  and  I  was 
in  utter  darkness  as  to  the  mode  of  getting  any  of 
the  other  things  from  a  teaspoon  to  a  cook.  How- 
ever, I  inquired  and  as  soon  as  I  learned  how,  I  set 
myself  to  work.  For  two  nights  I  slept  only  about 
three  hours  each,  and  I  had  the  satisfaction  of  report- 
ing to  Dr.  Letterman  at  the  end  of  three  days,  instead 
of  five,  that  I  was  ready.  On  the  fourth  day  I  had 
one  hundred  wounded  men  in  each  hospital.^ 

I  congratulate  you  in  this  more  enlightened  age  and 
as  students  in  this  fine  school  where  you  are  trained  and 
drilled  in  matters  which  we  had  to  cope  with  in  our  stumb- 
ling way,  by  dint  of  desperately  hard  work,  without 
guidance,  often  learning  only  by  our  bitter  mistakes. 

We,  the  few  surgeons  still  surviving  those  momentous 
four  years,  may  well  say  to  you  Morituri  salutamus. 

I  have  been  so  very  fortunate  as  to  live  during  the 
whole  period  of  the  greatest  revolution  surgery  has  ever 
passed   through.     How   strange   seem   these   words   of 

1  Keen,  Addresses  and  Other  Papers,  1905,  p.  424. 


154  CONTEMPORARY  SCIENCE 

Erichsen,  the  then  foremost  London  surgeon  and  Lister's 
early  chief  at  University  College  Hospital  uttered  in 
1874,  just  as  surgery  was  on  the  eve  of  its  very  greatest 
triumph. 

Surgery  in  its  mechanical  and  manipulative  proc- 
esses, in  its  art  in  fact,  is  approaching,  if  it  has  not 
already  attained  to,  something  like  finality  of  per- 
fection.^ 

Anesthesia  in  1846  and  1847  ^^^  robbed  operations  of 
the  terror  of  agonizing  pain.  Quick,  "slap-dash  surgery" 
— a  necessity  before  the  days  of  anesthesia — then  gave 
way  to  delicate,  painstaking,  artistic  surgery.  Antiseptics 
thirty  years  later  relieved  the  patients  from  the  terrors 
of  death  and  gave  to  the  surgeon  restful  nights  and  joy- 
ous days. 

Hence  when  I  received  the  kind  invitation  to  address 
you  it  seemed  to  me  that  I  could  possibly  render  you 
some  service  by  describing  the  state  of  surgery  "Before 
and  After  Lister,"  since  my  testimony  would  be  that  of 
an  eyewitness. 

When  the  Apostle  Paul  was  about  to  be  bound  and 
scourged  you  remember  that  he  claimed  immunity  as  a 
Roman.  "With  a  great  sum  obtained  I  this  freedom,'' 
explained  the  chief  captain.  "But  I/'  said  the  Apostle, 
with  justifiable  pride,  "was  free  born."  "With  a  great 
sum"  of  the  most  strenuous  labor  the  men  of  my  genera- 
tion acquired  the  knowledge  and  the  skill  and  the  immense 
satisfaction  of  the  antiseptic  and  aseptic  era — ^but  you, 
you  are  "free  born"  and  have  entered  into  a  rightful 
heritage  from  your  fathers.  "Before  Lister"  and  "After 
Lister"  in  the  surgical  calendar  are  the  equivalents  of 
^*B.c."  and  "a.d."  of  our  common  chronology. 

Modern  military  surgery  may  be  said  to  begin  with 
Ambroise  Pare  in  the  middle  of  the  sixteenth  century. 

2  Wrench,  Lister's  Life  and  Work,  p.  281. 


BEFORE  AND  AFTER  LISTER  155 

Gunpowder,  though  long  known,  had  been  used  in  war- 
fare to  any  large  extent  for  only  a  few  decades.  The 
belief,  shared  fully  by  Pare  himself,  that  such  wounds 
were  "poisoned,''  was  universal.  Treatment  was  directed 
to  the  destruction  of  the  supposed  poison  by  pouring 
boiling  oil  and  hot  pitch  into  such  wounds.  In  the  heat 
of  his  anger  at  the  inhumanity  of  the  new  weapons  he 
says  in  his  preface  to  Book  XL,  "Of  wounds  made  by 
gunshot  and  other  fiery  Engines  and  all  sorts  of  Wea- 
pons" :  ^ 

I  think  the  deviser  of  this  deadly  Engine  hath  this 
for  his  recompence  that  his  name  should  be  hidden 
by  the  darkness  of  perpetual  ignorance  as  not  merit- 
ing for  this  his  most  pernitious  Invention  Any  Men- 
tion from  Posterity. 

Yet  with  a  curious  inconsistency  he  immediately  gives 
the  name  of  a  German  monk  as  the  "deviser.*' 

Listen  to  his  quaint  story  of  how  he  discovered  that 
gunshot  wounds  were  not  poisoned.     In  1536 

it  chanced  on  a  time  that  by  reason  of  the  multitude 
that  were  hurt  I  wanted  this  Oil  ["oyl  of  Elders 
Scalding  hot  with  a  little  Treacle  mixed  therewith"]. 
Now  because  there  were  some  few  left  to  be  dressed 
I  was  forced  .  .  .  that  I  might  not  leave  them  un- 
drest  to  apply  a  digestive  made  of  the  yolk  of  an 
egg,  Oil  of  Roses  and  Turpentine.  I  could  not  sleep 
all  that  night  for  I  was  troubled  in  mind,  and  the 
dressing  of  the  precedent  day  (which  I  judged  unfit), 
troubled  my  thoughts ;  and  I  feared  that  the  next  day 
I  should  find  them  dead,  or  at  the  point  of  death  by 
the   poison   of   the  wounds.  .  .  .  Therefore   I   rose 

3  The  Works  of  that  Famous  Chirurgeon  Ambrose  Parey, 
translated  by  Th.  Johnson,  London,  1678,  p.  270. 


156  CONTEMPORARY  SCIENCE 

early  in  the  morning.  I  visited  my  Patients  and  be- 
yond expectation  I  found  such  as  I  had  dressed  with 
a  digestive  only,  free  from  vehemency  of  pain,  to 
have  had  a  good  rest  and  that  their  wounds  were  not 
inflamed  .  .  .  but  ...  the  others  that  were  burnt 
with  the  Scalding  Oyl  were  feverish  tormented  with 
much  pain  .  .  .  and  swoln.  When  I  had  many  times 
tried  this  in  divers  others,  I  thought  this  much,  that 
neither  I  nor  any  other  should  ever  cauterize  any 
I     wounded  with  Gunshot.* 

But  he  still  advocated  the  actual  cautery  for  arresting 
hemorrhage  even  down  to  early  in  1552.  But  later  in 
that  same  year  he  changed  his  practice  and  thus  describes 
his  introduction  of  the  ligature — a  famous  advance. 

I  confess  here  freely  and  with  great  regret  that 
heretofore  my  practice  has  been  entirely  different 
from  that  which  I  describe  at  present  after  amputa- 
tions. ...  I  advise  the  young  surgeon  to  abandon 
such  cruelty  and  inhumanity  and  follow  this  better 
method.  .  .  .  Having  several  times  seen  the  suture 
of  veins  and  arteries  for  recent  wounds  which  were 
attended  by  hemorrhage  I  have  thought  that  it  might 
be  well  to  do  the  same  after  the  amputation  of  a 
limb.  Having  consulted  in  reference  to  this  matter 
with  Etienne  de  la  Riviere,  Ordinary  Surgeon  to  the 
King,  and  other  surgeons  sworn  of  Paris,  and  having 
declared  my  opinion  to  them,  they  advised  that  we 
should  make  the  experiment  [espreuve]  on  the  first 
patient  that  we  had,  but  [note  his  cautious  uncer- 
tainty] but  we  would  have  the  cautery  all  ready  in 
case  of  any  failure  of  the  ligature.  I  have  done  this 
on  the  person  of  a  postilion  named  Pirou  Garbier, 
whose  right  leg  I  cut  off  .  .  .  following  a  fracture.** 

*  Johnson's  Pare,  p.  272. 

6  Malgaigne's  Pare,  Chap.  XXVI.,  pp.  227,  230. 


BEFORE  AND  AFTER  LISTER  157 

At  the  Siege  of  Danvilliers  ®  also  in  1552  he  records 
the  amputation  of  the  leg  of  a  gentleman  in  the  suite  of 
M.  de  Rohan  "without  applying  the  actual  cautery."  In 
another  place  ^  Pare  says  that  he  was  taught  this  new 
method  "by  the  special  favor  of  the  Sacred  Deity."  He 
also  refers  to  Galen's  advocacy  of  the  ligature.  After 
many  trials,  Pare  definitely  adopted  the  ligature  and  "bid 
eternal  adieu  to  all  hot  Irons  and  Cauteries." 

He  does  not  seem  to  have  lost  sleep  over  the  ligature 
as  he  did  sixteen  years  before  when  he  abandoned  the 
boiling  oil  and  the  hot  pitch.  Both  were  experiments  on 
human  beings.  "Human  vivisection"  would  have  been 
the  outcry  of  a  sixteenth-century  antivivisection  society. 
But  had  he  or  some  successor  not  made  these  experi- 
ments we  should  still  be  filling  gunshot  wounds  with  boil- 
ing oil  and  hot  pitch  and  searing  amputation  flaps  with 
the  actual  cautery.  How  much  greater  a  boon  to  humanity 
it  would  have  been  if  years  earlier  instead  of  experiment- 
ing in  both  cases  on  human  beings  first,  Pare  had  experi- 
mented on  a  few  animals  to  determine  whether  gunshot 
wounds  were  poisoned  and  whether  the  ligature  or  the 
cautery  was  the  best  means  of  arresting  hemorrhage. 

We  can  also  incidentally  learn  how  the  doctrine  of 
euthanasia  was  applied  in  Parens  time  in  the  case  of  the 
desperately  wounded  by  the  following  incident. 

In  his  first  campaign,  entering  a  stable  where  he  ex- 
pected to  put  up  his  own  and  his  man's  horses,  Pare 
found  four  dead  soldiers  and  three  propped  against 
the  wall,  their  features  all  changed,  and  they  neither 
saw,  heard  nor  spake,  and  their  clothes  were  still 
smouldering  where  the  gun-powder  had  burnt  them. 
As  I  was  looking  at  them  with  pity  there  came  an 
old  soldier  who  asked  me  if  there  was  any  way  to 
cure  them.    I  said  no,  and  then  he  went  up  to  them 

^Malgaigne's  Pare,  III,  698. 

7  Johnson's  Pare,  London,  1678,  Book  XII.,  Chap,  xxiv.,  p.  305. 


iS8  CONTEMPORARY  SCIENCE 

and  cut  their  throats  gently  and  without  ill  will  to- 
ward them.^ 

Leaping  over  three  and  a  half  centuries  of  only  moder- 
ate progress,  let  us  next  consider  the  state  of  surgery  a 
hundred  years  ago.  No  better  representative  perhaps 
could  be  chosen  than  John  Bell,  the  professor  of  surgery 
in  Edinburgh,  whose  "Discourses  on  the  Nature  and  Cure 
of  Wounds"  had  reached  a  third  edition  in  1812,  and  his 
''Principles  of  Surgery''  a  new  edition  in  1826,  to  which 
his  brother.  Sir  Charles  Bell,  also  contributed. 

In  the  former  he  states  that  tents  or  setons  were  much 
in  use  and  the  surgeons  "were  quite  delighted  with  see- 
ing prodigious  quantities  of  matter  spouting  out  when 
they  drew  their  spigot  away"  (p.  299). 

As  to  abdominal  wounds  he  says : 

Having  put  it  down  as  a  prognostic,  which  is  but 
too  well  confirmed,  by  much  melancholy  experience, 
that  wounds  of  the  belly  are  mortal,  there  is  no  rea- 
son why  we  should,  in  recording  our  cases,  take  any 
note  of  a  man  having  died  after  such  a  wound.  Death 
from  such  a  wound  is  a  daily  and  expected  occurrence 
and,  therefore,  is  not  marked;  but  if  we  find  that  a 
man  has  escaped,  are  we  not  to  record  every  such 
escape?  (p.  313). 

Per  contra,  to-day  recovery  has  been  achieved  after 
19  wounds  of  the  abdominal  viscera ! 

He  considers  wounds  of  the  joints  also  as  mortal,  and 
amputations  even  in  the  most  favorable  circumstances  did 
not  heal  under  four,  five  or  six  months ! 

In  his  "Principles  of  Surgery"  ^  he  pictures  the  wards 
of  a  hospital  as  follows : 

8  Paget's  Amhroise  Pari,  p.  31. 

» John  Bell's  Principles  of  Surgery,  new  edition,  with  com- 
ments by  Charles  Bell,  London,  1826,  p.  86. 


BEFORE  AND  AFTER  LISTER  159 

You  look  upon  limbs  variously  wounded,  but  all  of 
them  lying  out,  swollen,  suppurating,  fistulous,  rotting 
in  their  own  filth,  having  carious  bones,  bleeding 
arteries  and  a  profusion  of  matter;  the  patients  ex- 
hausted in  the  meanwhile,  with  diarrhea,  fever  and 
pain. 

Again  he  refers  to  a  wounded  limb  as  "soaking  in  sup- 
puration" and  again,  of  its  "lying  in  a  slush  of  matter 
and  foul  poultices." 

He  relates  the  case  of  an  officer  under  the  care  df 
Guerin,  a  celebrated  French  surgeon.  He  was  wounded 
by  a  ball  which  had  broken  the  fifth  rib  twice  and  tra- 
versed the  entire  chest.  After  dilating  the  wounds,  Guerin 
introduced  a  seton  ["a  great  strap  of  coarse  linen"], 

which,  of  course,  went  across  the  breast  as  a  bow- 
string crosses  a  bow,  and  this  seton  he  continued  to 
draw  with  a  perseverance  which  is  truly  wonderful 
from  the  first  day  to  the  thirty-eighth  day  of  the 
wound ;  during  all  of  which  time  the  patient's  suffer- 
ings were  dreadful  (p.  458). 

In  fifteen  days  the  patient  was  bled  twenty-six  times. 
After  the  removal  on  the  thirty-third  day  of  a  splinter 
of  bone,  which  had  been  imbedded  in  the  lung,  the  pa- 
tient, strange  to  say,  recovered  both  from  the  wound  and 
from  the  surgeon.  It  is  not  to  be  wondered  at  that  Bell 
condemns  such  treatment.  But,  as  we  have  seen,  it  ex- 
isted in  the  practice  of  reputable  surgeons. 

Erysipelas,  tetanus,  pyemia,  septicemia  were  rife.  Hos- 
pital gangrene  was  endemic  in  many  if  not  most  hospitals, 
due  to  inevitable  infection  in  practically  every  wound. 
Veritable  epidemics  were  frequent.  Is  it  any  wonder 
that  it  had  always  been  present  for  nearly  two  hundred 
years  in  the  Hotel  Dieu  in  Paris  when  there  were  often 
from  two  to  six  patients  (and  such  patients!)  in  one 
bed  ?    Passing  along  the  streets  of  Paris  even  during  the 


i6o  CONTEMPORARY  SCIENCE 

Crimean  War^^  "one  could  recognize  at  a  distance  a 
surgical  hospital  owing  to  the  stench  of  the  human  putrid- 
ity it  contained/'  In  the  surgical  wards,  "no  matter  how 
well  ventilated,  there  was  a  fetid  sickening  odor"  up  to 
the  days  of  Lister  himself,  wrote  Sir  Hector  Cameron, 
Lister's  house  surgeon  in  Glasgow.  Death  always  stalked 
grimly  behind  the  surgeon. 

Secondary  hemorrhage,  tetanus,  erysipelas,  septice- 
mia, pyemia  and  hospital  gangrene  were  never  all 
absent  .  .  .  and  at  times  pyemia  and  hospital  gan- 
grene became  alarmingly  epidemic.^^ 

After  vividly  describing  the  ravages  of  hospital  gan- 
grene Bell  then  vehemently  asks : 

What,  then,  is  the  surgeon  to  do?  Is  he  to  try 
experiments  with  ointments  and  plasters  while  the 
men  are  dying  around  him?  Is  he  to  seek  for 
washes  and  dressings  to  cure  such  a  disease  as  this? 
Is  he  to  expend  butts  of  wine  contending,  as  it  were, 
against  the  elements?  No!  Let  him  bear  this  al- 
ways in  mind,  that  no  dressings  have  ever  been 
found  to  stop  this  ulcer,  that  no  quantities  of  wine 
or  bark  which  a  man  can  bear  have  ever  retarded 
this  gangrene;  let  him  bear  in  mind  that  this  is  a 
hospital  disease,  that  without  the  circle  of  the  in- 
fected walls  the  men  are  safe;  let  him,  therefore, 
hurry  them  out  of  this  house  of  death ;  let  him  change 
the  wards,  let  him  take  possession  of  some  empty 
house  and  so  carry  his  patients  into  good  air ;  let  him 
lay  them  in  a  schoolroom,  a  church,  on  a  dunghill,  or 
in  a  stable ;  let  him  carry  them  anywhere  but  to  their 
graves.^^ 

10  Wrench's  Life  of  Lord  Lister,  p.  239. 

11  Cameron,  British  Medical  Jl,  Dec.  13,  1902,  p.  1844. 

12  Bell,  Principles  of  Surgery,  1826,  I.,  p.  149. 


BEFORE  AND  AFTER  LISTER  i6i 

To-day  we  do  not  even  know  the  bacteriology  of  this 
foul  disease.  I  saw  many  cases  of  it  during  the  Civil 
War,  but  since  1865  I  have  never  seen  a  single  case. 
There  has  been  no  opportunity  to  discover  its  germ  if,  as 
is  probable,  it  is  a  germ  disease.  Lister  made  its  return 
impossible. 

But  let  us  come  down  next  to  the  period  immediately 
before  Lister's  work. 

You  cannot  do  better  than  read  that  remarkable  and 
revolutionary  paper  entitled  "Hospitalism''  by  Sir  James 
Y.  Simpson,  of  Edinburgh,  published  in  1867.^^  It  was 
a  bombshell  whose  explosion  aroused  the  profession  as 
hardly  any  other  paper  in  my  lifetime.  The  controversy 
was  bitter  and  widespread.  Fortunately,  antisepsis  came 
close  upon  its  heels  and  has  forever  done  away  with  such 
a  disgrace. 

Simpson  collected  the  statistics  of  the  obstetrical  mor- 
taHty  in  hospitals  and  in  homes  with  the  following  start- 
ling result. 

Of    888,302    women    delivered    in   hospitals,    30,394 

died  or  i  in  29 — 3.4  per  cent. 
Of  934,781   delivered  at  home,  4,045  died,  or  i  in 

212 — 0.47  per  cent. 

The  reason  for  the  greatly  increased  mortality  in  ma- 
ternity hospitals — over  seven  times  greater  than  in  in- 
dividual homes — was  chiefly  puerperal  fever.  After 
Oliver  Wendell  Holmes  (1843)  ^^^  Semmelweiss  (1861) 
had  attacked  the  evil,  Pasteur  finally  in  1879  showed  its 
bacteriological  cause  and  gave  it  the  coup  de  grace. 

The  0.47  per  cent,  of  Simpson's  home  cases  has  been 
reduced  to  0.15  per  cent,  and  even  0.08  per  cent,  in  the 
maternity  hospitals  of  to-day ! 

But  his  chief  assault  was  upon  the  surgeons.  He  ana- 
lyzed the  four  main  amputations — arm,  forearm,  thigh 

^9  Simpson's  Works,  Vol.  II.,  p.  345. 


i62  CONTEMPORARY  SCIENCE 

and  leg — and  excluded  amputations  at  joints  and  all  the 
minor  amputations  (fingers,  toes,  etc.). 

Of  2,089  such  amputations  in  hospitals,  855   died, 

or  41  per  cent. 
Of  2,098  in  country  practice,  222  died,  or  10.8  per 

cent. 

The  latter  were  collected  from  374  country  practitioners, 
thus  eliminating  the  personal  equation.  The  diflFerence 
was  clearly  due  to  the  crowding  and  lack  of  sanitation  in 
the  hospitals  of  that  day. 

He  gives  two  very  interesting  tables.  The  first  is  most 
instructive  in  showing  the  results  in  the  then  unsanitary 
state  of  all  hospitals. 

Mortality  After  the  Four  Selected  Amputations  in  Pro- 
portion to  the  Number  of  Beds  in  the  Hospitals 

In  the  large  Parisian  hospitals 62  in  100  die 

In  British  hospitals  with  300  to  600  beds. 41  in  100  die 
In  British  hospitals  with  300  to  201  beds. 30  in  100  die 
In  British  hospitals  with  200  to  loi  beds. 23  in  100  die 
In  British  hospitals  with  100  to  26  beds. .  18  in  100  die 
In  British  hospitals  with  25  beds  or  less. .  14  in  100  die 
In  isolated  rooms  in  country  practice.  .11  in  100 die 

In  the  second  he  tabulates  the  mortality  according  to  the 
experience  of  the  operator. 

Death  Rate  After  the  Same  Four  Amputations  in 
Accordance  with  the  Experience  of  the  274 
Operators 
Those  who  had  done  less  than  6  amputa- 
tions  lost  I  in     7 

Those  who  had  done  from  6  to  12  amputa- 
tions  lost  I  in    9 

Those  who  had  done  12  or  more  amputa- 
tions  lost  I  in  12 

What  an  argument  for  the  necessity  for  a  year  in  a 


BEFORE  AND  AFTER  LISTER  163 

hospital  for  the  recent  graduate  before  allowing  him  full 
liberty  of  action ! 

In  France  matters  were  as  bad  if  not  even  worse.  T. 
Holmes  and  Bristowe  in  1861  had  found  that  in  Paris, 
of  102  of  the  four  amputations  in  question,  67  died,  a 
mortality  of  65.7  per  cent.,  or  two  out  of  every  three. 
Out  of  1,656  amputations  in  the  Paris  hospitals  collected 
by  Malgaigne  and  Trelat  803  died,  48.5  per  cent.,  almost 
one  in  every  two  (Simpson,  p.  291). 

To-day,  how  entirely  changed  is  all  this.  Listerism  has 
transformed  what  Bell  well  called  "Houses  of  Death" 
into  "Havens  of  Safety."  No  home,  however  wealthy  its 
inmate,  can  be  as  sanitary,  as  surgically  clean  or  give  as 
good  results  as  a  modern  hospital. 

The  best  evidence  of  the  truth  of  this  statement  I  can 
give  you  is  the  statistics  of  Dr.  W.  L.  Estes,^*  of  South 
Bethlehem,  Pennsylvania.  They  are  of  especial  value  in 
that  they  are  the  statistics  of  the  same  surgeon  in  the  same 
hospital  and  on  the  same  class  of  patients.  He  reports 
the  result  in  724  major  amputations.  In  616  single  am- 
putations there  were  28  deaths,  a  mortality  rate  of  4.54 
per  cent.  Of  469  of  the  four  selected  amputations,  25 
died,  a  mortality  of  5.3  per  cent.  Of  synchronous  double, 
triple  and  one  quadruple  amputation,  many  of  them  com- 
plicated with  other  wounds  and  operations,  there  were 
108,  with  19  deaths,  a  mortality  of  only  18  per  cent.  It 
is  very  noticeable  that  in  an  earlier  paper  in  1894  in  which 
he  had  reported  the  first  46  cases  of  synchronous  double, 
triple  and  quadruple  and  complicated  amputations,  there 
were  13  deaths,  28.3  per  cent.,  whereas  from  1894  to  1913 
in  the  last  62  such  cases  there  were  only  six  deaths,  a 
mortality  of  9.6  per  cent.,  showing  again  the  value  of  still 
larger  experience  even  to  an  already  experienced  surgeon. 
In  the  second  series  there  was  no  quadruple  amputation. 

But  as  officers  of  the  Medical  Corps  of  the  Army  you 
will  be  especially  interested  in  the  facts  as  to  military 

'^^  Annals  of  Surgery,  July,  1913. 


i64  CONTEMPORARY  SCIENCE 

surgery  before  and  after  Lister.  Capt.  Louis  C.  Duncan 
of  our  corps  published  a  very  interesting  and  comprehen- 
sive article  ^^  just  before  the  present  European  war  broke 
out. 

He  states  that  in  Motley's  "Rise  of  the  Dutch  Republic" 
in  three  volumes  covering  "30  years  of  almost  constant 
sanguinary  warfare"  in  the  sixteenth  century  he  "never 
once  alludes  to  an  army  surgeon  or  an  army  hospital" ! 
The  surgeons  were  undoubtedly  not  officially  attached  to 
the  army,  but  were  in  the  suites  of  kings,  princes  or 
great  nobles,  as  was  Pare,  in  the  same  century. 

To  Sir  James  McGrigor  in  the  Peninsular  Campaign 
(1808-11)  only  fifty  years  before  our  Civil  War,  is  given 
the  credit  by  Duncan  of  first  collecting  accurate  military 
medical  statistics. 

One  hundred  and  fifty  years  ago  25  per  cent,  or  more 
of  the  wounded  died.  In  the  Civil  War  and  in  the  Franco- 
Prussian  War  of  1870-1  the  rate  had  fallen  to  about  15 
per  cent,  while  to-day  up  to  the  present  war  not  over  5 
or  6  per  cent,  die  of  wounds. 

The  Crimean  War  will  always  be  an  example  of  utter 
inefficiency  in  the  English  and  even  worse  in  the  French 
army.  Its  one  bright  spot  is  the  splendid  epoch-making 
work  of  a  woman,  Florence  Nightingale,  whose  labors 
were  unceasing  and  efifective.  Every  war  since  then  has 
seen  less  sickness  and  fewer  deaths  because  of  what  she 
then  accomplished. 

Chenu,  the  French  medical  historian  of  that  war,  has 
made  one  curious  and  interesting  calculation,  partly  offi- 
cial, partly  estimated.  The  number  of  projectiles  of  all 
kinds  actually  fired  he  gives  as  89,595,363.  The  total 
number  of  killed  and  wounded  was  175,057.  This  would 
show  that  it  took  512  projectiles  to  kill  or  wound  one 
man.  Such  a  disproportion  would  more  than  justify  a 
cartoon  during  our  Civil  War.     Two  soldiers  were  sur- 

'^'^  Journal  of  the  Military  Service  Institutions  of  the  United 
States,  March-April,  1914. 


BEFORE  AND  AFTER  LISTER  165 

prised  by  a  hundred  of  the  enemy.  One  proposed  t6 
the  other  to  run  for  it.  "No,"  was  the  cool  reply,  "There's 
no  danger,  for  they  say  only  one  ball  in  200  ever  hits  and 
there  are  only  one  hundred  of  those  fellows." 

Duncan's  figures  give  82,901  British  soldiers  sent  to  the 
Crimea,  but  the  average  strength  was  only  34,559,  or  only 
about  40  per  cent.,  of  effectives.  The  killed  (2,755)  ^^^ 
the  deaths  from  wounds  (2,019)  gave  a  battle  death  rate 
of  69  per  1,000  per  annum,  while  the  disease  death  rate 
rose  to  230  per  1,000  per  annum. 

In  all,  300  men  out  of  each  1,000  perished  each 
year! 

But  the  French  statistics  are  still  worse.  While  315,000 
were  sent  out,  the  average  strength  was  less  than  104,000 
effectives,  or  only  33  per  cent.  The  killed  numbered 
7,607  and  the  deaths  from  wounds  8,813.  The  battle 
death  rate  was  70,  the  disease  death  rate  341,  per  1,000 
per  annum.    Over  6,000  died  from  typhus  alone. 

Could  there  be  a  nobler  example  of  the  altruism  of  our 
profession — an  altruism  often  tested  and  never  in  vain — 
than  that  shown  by  Drs.  Richard  P.  Strong,  Thomas  W. 
Jackson,  and  many  other  doctors  and  trained  nurses,  and 
now  finally  by  the  chief  of  our  corps — the  friend  of  hu- 
manity— Major  General  William  C.  Gorgas  in  hastening, 
regardless  of  danger,  to  the  relief  of  Serbia,  sorely  smitten 
by  the  deadly  typhus  fever? 

Chenu's  report  gives  a  summary  of  the  English  as  well 
as  the  French  losses.  Comparing  it  with  Simpson's  civil 
statistics  eleven  years  later  the  mortality  of  the  four  se- 
lected amputations  (arm,  forearm,  thigh  and  leg)  was  as 
follows :  Of  2,089  of  these  four  amputations  in  civil  hos- 
pitals the  mortality  in  Simpson's  table  was  41  per  cent. 
In  the  Crimean  War  among  the  British  there  were  460 
such  amputations  and  183  deaths,  or  40  per  cent.  In  the 
French  army  there  were  5,972  such  amputations  with 
4,023  deaths,  a  mortality  of  67.4  per  cent.    In  both  armies 


i66  CONTEMPORARY  SCIENCE 

disarticulation  at  the  hip-joint  had  a  mortality  of  lOO 
per  cent.,  i.e.,  every  case  died.  It  is  instructive  also  to 
compare  the  fate  of  those  who  had  an  amputation  of  the 
thigh  ( 1,666  French  cases)  with  a  mortality  of  92  per 
cent.,  and  487  cases  treated  conservatively,  i.e.,  without 
amputation,  with  a  mortality  of  only  70  per  cent. ! 

In  our  Civil  War  Duncan  quotes  the  figures  of  Fox, 
which  are  "the  latest  revised  statistics  and  are  all  larger 
than  those  of  the  Medical  and  Surgical  History  of  the 
War."  The  average  strength  of  the  Union  Armies  was 
806,755,  and  the  deaths  359,528,  of  whom  67,058  were 
killed  in  battle  and  43,012  died  of  wounds.  This  gives  a 
battle  death  rate  of  33  per  1,000  per  annum.  The  disease 
death  rate  was  65  per  1,000  per  annum.  The  case  death 
rate  from  disease  was  only  3.4  per  cent.,  a  very  low  figure. 

I  can  testify  to  the  excellent  condition  of  the  Civil  War 
hospitals,  of  which  I  saw  many,  but  only  in  the  East. 
When  I  say  "excellent  condition"  it  must  be  with  the 
reserve  that  we  knew  nothing  as  to  bacteriology,  which 
did  not  exist,  nor  of  infection,  which  was  utterly  un- 
known as  to  its  causes  and  prevention.  The  general  sani- 
tary conditions,  and  by  this  I  mean  shelter,  ventilation, 
cleanliness,  good  food,  as  good  nursing  as  intelligent  order- 
lies could  give,  etc.,  were  all  excellent.  But  the  surgical 
conditions  as  we  now  know  were  simply  dreadful.  Prac- 
tically every  wound  suppurated,  and  in  summer  I  have 
seen  many  wounds  swarming  with  squirming  maggots  as 
large  as  chestnut  worms— disgusting,  but,  fortunately, 
not  especially  dangerous. 

In  my  "Surgical  Reminiscences  of  the  Civil  War"  ^^ 
I  have  given  many  statistics  taken  from  the  official  Medi- 
cal and  Surgical  History  of  the  War,  a  few  of  which  I 
will  reproduce  that  you  may  see  what  blessed  conditions 
you  "free  born"  men  have  inherited.  Pyemia  (blood- 
poisoning)  was  one  of  our  worst  scourges.  There  were 
2,818  cases,  and  of  these  only  71  recovered,  a  death  rate 

^6  Keen,  Addresses  and  Other  Papers,  1905,  p.  420. 


BEFORE  AND  AFTER  LISTER  167 

of  97.4  per  cent.  Few  of  you  probably  have  seen  even 
one  such  case.  I  have  given  a  matter-of-fact  description 
of  it  in  my  "Surgical  Reminiscences,"  but  if  you  wish  to 
see  it  sketched  by  a  master's  hand  read  that  most  touch- 
ing and  beautiful  of  all  medical  stories  I  know — "Rab 
and  His  Friends,"  by  dear  old  Dr.  John  Brown,  of  Edin- 
burgh. He  vividly  paints  the  sudden  change  in  the  wound, 
the  pulse,  the  eye,  the  mind,  on  and  on,  worse  and  worse, 
until  "that  animula,  blandula,  vagiila,  hospes  comesque 
was  about  to  flee." 

Tetanus  had  a  mortality  of  89.3  per  cent.  Of  amputa- 
tions at  the  hip-joint  83.3  per  cent.  died.  Trephining  had 
a  mortality  of  61  per  cent.  Even  of  ligations  of  the  fe- 
moral artery,  374  in  number,  281  died,  or  over  75  per 
cent.  Of  2,235  cases  of  secondary  hemorrhage,  61.7  per 
cent.  died.  Hospital  gangrene,  of  which  there  were  sev- 
eral hundred  cases,  had  only  a  mortality  of  about  25  per 
cent.,  because  we  early  learned  the  correct  though  empiri- 
cal treatment,  viz.,  the  application  of  the  actual  cautery, 
pure  bromine,  strong  nitric  acid  or  similar  destructive 
agents  which  killed  the  germ,  whatever  it  was,  and  ar- 
rested the  disease. 

The  Franco-Prussian  War  of  1870-71  was  marked  by 
notable  progress  in  military  sanitation  in  the  German  army, 
yet  in  spite  of  this  there  were  74,205  cases  of  typhoid 
fever,  almost  10  per  cent,  of  the  entire  average  strength 
(788,213)  and  8,904  deaths,  a  mortality  of  11.3  per  cent. 

Surgically  the  results  were  nothing  to  boast  of.  Lis- 
terism  had  as  yet  made  but  little  progress  in  the  profes- 
sion. Carbolic  acid  was  used  to  some  extent,  but  there 
was  no  thorough  antiseptic  system,  for  the  germ  theory 
was  as  yet  neither  understood  nor  accepted. 

Of  tetanus  there  were  294  cases,  and  268  died,  a  mor- 
tality of  91. 1  per  cent. 

The  total  of  the  four  selected  amputations  was  2,194 
with  1,196  deaths,  a  mortality  of  54.5  per  cent. — over 
one-half. 


l68  CONTEMPORARY  SCIENCE 

Disarticulation  at  joints  showed  an  average  mortality- 
of  56  per  cent.  Fifteen  amputations  at  the  hip-joint  gave 
a  mortality  of  100  per  cent.,  and  resections  claimed  40.2 
per  cent,  of  deaths.  Even  at  the  knee-joint  Stromeyer 
amputated  36  times  with  36  deaths  and  Nussbaum  34 
times  with  34  deaths.^^ 

The  French  results  were  naturally  worse,  for  their 
armies  were  constantly  being  defeated  and  retreating, 
and,  especially  in  the  latter  part  of  the  war,  they  consisted 
largely  of  volunteers,  while  the  Germans  were  mostly 
veterans  of  the  Schleswig-Holstein  and  Austro-Prussian 
wars. 

Of  the  Boer  War  (1899-1901)  only  two  features  need 
be  noticed.  First,  that  typhoid  attacked  57,684  men  and 
killed  8,022,  while  the  Boers  only  killed  7,781.  Bacteria 
were  more  deadly  than  bullets,  as  Osier  has  said. 

Secondly,  the  modern  missile  was  for  the  first  time  in 
general  use,  with  the  result  that  instead  of  about  15  per 
cent,  of  the  wounded  losing  their  lives,  only  about  8.8 
per  cent.  died.  The  wounds  from  the  new  missile  were 
much  less  severe  and  healed  more  quickly  than  ever  be- 
fore. The  first  aid  packet  also  had  come  to  the  aid  of  the 
soldier. 

The  Spanish  American  War,  surgically  speaking,  was 
of  little  moment,  as  the  numbers  killed  and  wounded  were 
too  small  to  make  the  statistics  of  any  great  value,  but  it 
is  gratifying  to  find  that  only  4.6  per  cent,  of  the  wounded 
died. 

Typhoid,  however,  held  high  carnival.  It  caused  86.24 
per  cent,  of  all  the  deaths !  Happily  we  can  say  that  here- 
after— thanks  chiefly  to  the  anti-typhoid  inoculations — 
there  will  never  be  another  such  holocaust.  (Vide  Lec- 
ture II.) 

The  statistics  of  the  Russo-Japanese  War  also  need 
detain  us  for  only  a  moment.  I  shall  only  quote  the 
Japanese  ofBcial  statistics,  as  given  by  Major  Lynch,  of 

17  Wrench's  Lister,  p.  236. 


BEFORE  AND  AFTER  LISTER  169 

our  army/^  There  were  47,387  killed.  Of  173,425 
wounded  11,500  died,  a  mortality  of  6.7  per  cent.  The 
killed  and  those  who  died  of  wounds  numbered  in  all 
58,887,  while  the  deaths  from  disease  numbered  only 
27,158,  a  remarkable  showing. 

The  present  war  naturally  has  yielded  so  far  very  few 
statistics.  These  can  only  be  collected  and  tabulated  after 
some  years  of  peace.  So  far  as  I  can  judge,  I  fear  that, 
while  the  mortality  from  disease  (except  perhaps  from 
typhus,  especially  in  Serbia)  will  be  less  than  in  former 
wars,  the  military  conditions  are  such  that  the  larger  num- 
ber of  artillery  wounds,  the  unavoidable  delay  in  gather- 
ing the  wounded  into  hospitals,  the  apparent  absence  of 
any  truce  for  collecting  the  wounded  and  burying  the 
dead,  and  the  virulent  infection  from  the  soil  may  result 
in  a  large  mortality  rate  and  possibly  a  larger  percentage 
than  in  previous  wars  in  spite  of  the  benefits  of  Listerism. 
But  were  the  first-aid  packet  and  the  Listerian  treatment 
not  available  the  mortality  ratio  in  this  present  horrible 
war  unquestionably  would  be  far  greater  than  that  which 
will  be  recorded. 

This  short  resume  gives  us  some  idea  of  surgical  condi- 
tions preceding  the  great  revolution  inaugurated  by  Lister 
to  which  we  will  next  proceed. 

LECTURE   II.,   AFTER   LISTER 

Yesterday  the  dominant  note  was  one  of  despair  and 
defeat.  To-day  the  dominant  note  shall  be  one  of  joy 
and  victory. 

Instead  of  hospitals  reeking  with  pus  and  emptied  by 
death,  of  operation  after  operation,  when  the  roll  was 
called,  reporting  a  mortality  of  40  per  cent.,  50,  75,  90, 
and  even  100  per  cent. — ^we  have  hospitals  of  immaculate 
whiteness  and  emptied  by  quick  recovery,  while  the  roll- 
call  of  operations  reveals  very  few  mortalities  exceeding 

^^  Reports  of  Military  Observers  attached  to  the  Armies  in 
Manchuria  during  the  Russo-Japanese  War,  Part  IV.,  p.  399. 


I70  CONTEMPORARY  SCIENCE 

10  per  cent. ;  most  of  them  having  fallen  to  5  per  cent.,  2 
per  cent.,  i  per  cent.,  and  even  small  fractions  of  i  per 
cent. 

The  story  of  Lister's  work  as  recorded  in  his  successive 
papers  ^  is  one  of  the  most  fascinating  in  all  surgery.  His 
earliest  studies,  from  1853  to  1863,  were  in  physiology 
and  pathology.  Next  he  took  up  his  researches  on  putre- 
faction (or  as  we  should  now  say  infection  and  suppura- 
tion) which  led  to  his  devising  the  antiseptic  system.  He 
was  influenced  to  make  these  observations  and  experi- 
ments, which  he  applied  with  such  signal  success  to  surgi- 
cal problems,  by  Pasteur's  earlier  researches.  He  always 
cheerfully  acknowledged  his  debt  to  the  eminent  French- 
man. When  a  student  in  Paris  in  1865  I  knew  Pouchet 
fils  and  was  an  interested  spectator  in  the  fight  between 
Pasteur  and  Pouchet's  father  as  to  spontaneous  genera- 
tion. Lemaire's  book  on  "Acide  Phenique"  (carbolic 
acid)  was  published  in  that  same  year. 

Bacteriology  did  not  exist  as  a  science,  but  Pasteur, 
Lister  and  a  few  of  the  elect  in  the  upper  realms  of 
imagination  saw  the  "germs"  or  "microbes"  and  firmly 
believed  them  to  be  the  cause  of  infection.  In  1900,  at 
the  age  of  seventy-three,  Lister  restated  his  earlier  work  ^ 
and  illuminated  it  by  many  observations,  experiments  and 
drawings  made  in  these  early  years,  but  first  published 
fifty  years  after  they  were  made. 

If  you  wish  to  know  the  man,  his  fertility  in  devising 
new  and  convincing  experiments,  and  his  mental  acumen 
in  interpreting  them  "read,  mark,  learn  and  inwardly  di- 
gest" that  paper  and  use  it  as  a  model. 

Pare  in  his  naive  way  tells  us  that  he  sought  various 
apphcations  which  might  "mitigate  the  pains  [of  his  pa- 
tients] and  happily" — mark  the  word  ''happily" — "bring 
them  to  suppuration."  That  is  the  "laudable  pus"  of  the 
pre-Listerian  days.    Lister,  on  the  contrary,  believing  that 

1  Lister's  Collected  Papers,  2  vols.,  Oxford,  1909. 

2  Brit.  Med.  Jour.,  1900,  II.,  969. 


BEFORE  AND  AFTER  LISTER  171 

infection  and  suppuration  were  evils,  and  avoidable  evils, 
sought  by  various  means  to  prevent  them.  But  he  says 
"all  my  efforts  [during  his  work  in  Glasgow,  1860-69] 
proved  abortive,"  and  then  adds  significantly  ''as  I  could 
hardly  wonder  when  I  believed  zvith  che^nists  generally 
that  putrefaction  was  caused  by  the  oxygen  of  the  air." 

They  and  he  were  deeply  impressed  with  the  absence  of 
putrefaction  in  simple  fractures  when  the  air  and  its 
oxygen  had  no  access  to  the  fracture.  In  my  own  lectures, 
as  I  often  used  to  express  it,  "The  very  best  antiseptic 
dressing  is  an  unbroken  skin."  In  compound  fractures 
on  the  other  hand  when  the  air  and  its  oxygen  had  access 
to  the  lesion,  putrefaction  always  took  place  and  caused 
a  frightful  mortality. 

To  test  this  supposed  noxious  influence  of  oxygen  he 
devised  many  experiments,  and  among  them  one  which 
may  be  well  called  an  "experimentum  crucis."  He  filled 
four  flasks  one-third  full  of  urine  (a  quickly  putrescible 
liquid)  and  drew  out  the  necks  to  tubes  one-twelfth  of 
an  inch  in  diameter.  All  these  tubes  were  left  open. 
Three  of  these  long  necks  he  bent  at  various  angles  down- 
wards; the  fourth  was  left  vertical  upwards  and  also 
open.  He  then  boiled  all  four  flasks  and  awaited  the  re- 
sult. The  air  and  its  oxygen  had  free  access  to  the  urine, 
being  slowly  drawn  in  during  the  colder  night  hours  and 
driven  out  in  the  warmer  daytime.  Any  supposed  "germs" 
floating  in  the  air,  he  reasoned,  being  heavier  than  air, 
could  not  climb  up  the  slanting  neck  and  fall  into  the 
liquid.  In  a  short  time  the  urine  in  the  flask  with  the 
vertical  open  neck  was  decomposed,  but  the  other  three 
flasks,  also  with  open  necks  but  bent  downward,  remained 
undecomposed  for  years!  ^  They  were  finally  destroyed 
by  a  fire  in  the  laboratory. 

Could  there  be  a  more  convincing  proof  that  the  oxygen 

3  For  a  fuller  account  of  this  interesting  experiment  with  ref- 
erences see  my  Animal  Experimentation  and  Lledical  Progress, 
pp.  204-205. 


172  CONTEMPORARY  SCIENCE 

had  no  influence  whatever  in  producing  putrefaction,  but 
that  it  was  due  to  living  matter,  "germs,"  in  the  air?  It 
was  a  fine  instance  of  the  "scientific  use  of  the  imagina- 
tion." "Germs"  had  been  observed  from  time  to  time, 
but  had  not  been  generally  accepted  as  the  vera  causa  of 
putrefaction.  The  experiment  just  related  was  tried  about 
1867.  The  commonest,  all-pervading  germs,  the  staphy- 
lococcus and  streptococcus,  were  not  identified  and  proved 
to  be  the  chief  pyogenic  (pus-producing)  organisms  until 
1881,  fourteen  years  after  Lister  had  seen  them  so  clearly 
with  his  mind's  eye!  Even  in  1898  when  I  published  my 
"Surgical  Complications  and  Sequels  of  Typhoid  Fever" 
I  had  to  prove  by  elaborate  citations  of  experimental  and 
clinical  evidence  that  the  typhoid  bacillus  itself  could  cause 
suppuration,  and  that  it  had  actually  been  observed  in  the 
circulating  blood — for  the  past  ten  years  or  more  a  work 
of  supererogation. 

From  Glasgow  Lister  went  to  Edinburgh  (1869) 
as  the  successor  of  his  father-in-law,  Syme,  and  con- 
tinued to  experiment,  to  practise  and  to  publish,  but 
only  a  few  were  convinced,  among  them  being  Syme 
himself. 

On  the  continent  in  the  early  70's  Saxtorph  in  Copen- 
hagen, Thiersch  in  Leipzig,  Volkmann  in  Halle,  Nuss- 
baum  in  Munich,  and  Championniere  in  Paris  were  among 
Lister's  earliest  and  enthusiastic  disciples.  In  America 
not  much  attention  was  paid  to  his  work  until  he  visited 
Philadelphia  in  September,  1876,  to  attend  the  Interna- 
tional Medical  Congress  held  in  connection  with  the  Cen- 
tennial Exhibition.  He  was  made  president  of  the  Sec- 
tion on  Surgery  and  read  a  paper  on  the  antiseptic 
method. 

At  that  time  I  heard  him  and  became  fully  convinced 
of  the  truth  of  the  "germ  theory"  and  of  the  value  of  his 
antiseptic  method.  When  I  went  on  duty  at  St.  Mary's 
Hospital,  October  i,  1876,  I  adopted  the  system  (and  was 
the  first  surgeon  in  Philadelphia  to  do  so)  and  have  never 


BEFORE  AND  AFTER  LISTER  173 

abandoned  it.  For  me  it  changed  surgery  from  Purgatory 
to  Paradise. 

But  the  reception  given  to  his  paper  at  our  congress 
was  z  lything  but  enthusiastic.  The  only  surgeon  who 
practically  accepted  Lister's  method  was  that  excellent 
St.  Louis  surgeon,  John  T.  Hodgen.  But  so  hazy  were 
the  general  ideals  of  bacteria  that  in  his  own  paper  Hod- 
gen speaks  only  of  "germs"  and  "germinal  matter"  and 
had  no  idea  of  bacteriology  as  we  know  it,  for  the  science, 
and  even  its  name,  did  not  yet  exist. 

In  the  discussion  of  Hodgen's  paper  Hewson  advocated 
his  then  well-known  views  on  the  value  of  dry  earth  as  an 
"antiseptic."  Canniff  of  Toronto  rejected  in  toto  the 
germ  theory  of  putrefaction.  Frank  Hamilton,  of  New 
York,  while  claiming  extraordinarily  good  results  from 
the  open-air  treatment  and  the  warm- water  treatment  and 
other  rival  methods,  "damned  with  faint  praise"  the  an- 
tiseptic method.  Kinloch,  of  Charleston,  took  the  same 
attitude;  Carpenter,  of  Pottsville,  a  Civil  War  surgeon, 
advocated  chlorine  in  septic  cases.  Others  sang  paeans 
in  praise  of  "perfect  cleanliness"  and  said  they  "used  both 
carbolic  and  salicylic  acids,  but  not  for  the  purpose  of 
excluding  germs."  In  the  discussion  on  Lister's  paper. 
Van  Buren,  of  New  York,  doubted  the  safety  of  the 
spray  in  hernia  and  abdominal  sections  and  Satterthwaite, 
of  New  York,  rejected  the  germ  theory  of  putrefaction. 

In  1877  Girard,  of  the  U.  S.  Army,*  became  the  en- 
thusiastic supporter  of  Listerism. 

In  1880  Markoe,  of  New  York,  while  admitting  the  fine 
results  of  Listerism,  spoke  of  "its  somewhat  arrogant 
pretension  to  be  the  true  and  only  gospel  of  the  surgery 
of  wounds."  ® 

In  1882  Listerism  was  again  discussed  in  the  American 
Surgical  Association.  Briggs,  of  Nashville,  endorsed  Lis- 
ter's method  as  "an  epoch  in  surgery."    Yet  so  limited  was 

*  Circular  No.  3,  Surgeon  GeneraFs  Office,  August  20,  1877. 

5  Amer.  Jour.  Med.  ScL,  LXXIX.,  1880,  p.  305. 


174  CONTEMPORARY  SCIENCE 

our  knowledge  of  "germs"  even  then  that  warfare  was 
waged  only  upon  those  "in  the  air."  When  these  could  be 
excluded  he  said  "putrefaction  .  .  .  fails  to  occur."  Yet 
Briggs  qualifies  his  endorsement  by  saying  that  the 

supremacy  [of  the  antiseptic  method  as  contrasted 
with  other  methods  of  treatment]  .  .  .  cannot  be 
demonstrated  by  statistics  .  .  .  and  the  present  un- 
settled opinion  concerning  the  proper  status  of  his 
[Lister's]  method  is  due  in  great  measure  to  that 
fact. 

He  emphatically  dissented  from  the  germ  theory,  and 
added : 

Carbolic  acid  is  the  keystone  of  the  Listerian  wound 
treatment.  .  .  .  The  germ  theory  is  at  fault  and 
furnishes  a  very  unstable  foundation  for  a  system  of 
wound  treatment. 

Moore,  of  Rochester,  N.  Y.,  proposed  to  exclude  the 
air 

by  passing  carbonic  acid  gas  directly  into  the  place 
where  the  operation  is  to  be  performed.  In  conse- 
quence of  its  being  heavier  than  the  atmosphere  it 
preoccupies  the  space  (  !). 

Campbell,  of  Georgia,  "did  not  believe  that  bacteria 
^  .  .  are  the  cause  of  that  condition  [suppuration]." 
The  various  men  named  were  among  our  foremost  Ameri- 
can surgeons. 

Lister's  opponents  entirely  missed  the  great  fundamen- 
tal facts  underlying  the  germ  theory  and  Lister's  anti- 
septic method,  vi:^.,  that  infection  in  all  its  various  forms 
was  always  of  bacterial  origin — a  wholly  novel  and  mo- 
mentous idea.  Each  form  of  infection,  e.g.,  tetanus, 
tuberculosis,  typhoid,  etc.,  it  was  soon  proved,  arose  in- 


BEFORE  AND  AFTER  LISTER  i:'5 

variably  and  solely  from  its  own  specific  kind  of  germ. 
Whether  carbolic  acid  or  any  other  germicide  was  the 
best  was  a  mere  matter  of  detail  and  not  of  principle. 

In  commenting  on  this  discussion  in  which  one  promi- 
nent speaker  is  said  to  have  asserted  that  Listerism  "is 
now  dead" — a  remark  I  do  not  find  in  the  Transactions — 
The  Lancet,^  a  belated,  but  then,  and  ever  since,  a  real 
convert,  truly  said: 

Surely  it  is  too  late  in  the  day  to  contest  the  truth 
of  the  germ  theory. 

Yet  even  a  year  later  (1883)  ^t  the  American  Surgical 
Association  while  B.  A.  Watson,  of  Jersey  City,  fully 
accepted  Listerism,  other  prominent  surgeons  of  Phila- 
delphia, New  York,  New  Orleans,  Mobile,  and  other  cities 
even  declared  in  the  discussion  that  no  surgeon  in  their 
cities  or  states  used  the  method.  McGraw,  of  Detroit; 
Dawson,  of  Cincinnati ;  Campbell,  of  Georgia ;  Prince,  of 
Illinois,  were  "doubting  Thomases/'  while  Kinloch,  of 
Charleston,  and  Nancrede,  then  of  Philadelphia,  advo- 
cated it. 

But  if  its  progress  was  obstructed  in  the  United  States, 
its  foes  in  Great  Britain  were  even  more  strenuous  and 
for  a  season  more  successful. 

In  spite  of  the  striking  results  in  Glasgow  and  in 
Edinburgh  Lister  was  looked  at  askance  as  "unortho- 
dox." 

In  1875  ^^^  Lancet  '^  had  said 

there  is  less  antiseptic  surgery  practised  in  the  metro- 
politan hospitals  than  ever  there  was. 

At  the  Clinical  Society  ®  in  a  debate  on  antiseptic  sur- 

«  July  1,  1882,  p.  1088. 

7  October  16,  1875,  p.  565. 

8  Lancet,  October  30,  1875,  p.  628. 


176  CONTEMPORARY  SCIENCE 

gery  in  1875,  Mr.  Maunder  said  with  a  fine,  but,  as  the 
event  showed,  a  too  precipitate  sarcasm: 

Mr.  Lister  expects  to  prevent  traumatic  fever  and 
.  .  .  suppuration. 

Timothy  Holmes,  while  professing  to  have  used  anti- 
septics "for  some  years,"  declared  his  disbelief  in  Mr. 
Lister's  theory  with  regard  to  "germs.*'  The  Lancefs 
editorial  on  the  debate  said  it  was  "evident  that  few  of 
the  speakers  either  place  faith  in  Lister's  theory  or  carry 
out  his  practice  in  full." 

After  eight  years  in  Edinburgh  Lister  was  chosen  pro- 
fessor of  surgery  in  King's  College,  London,  in  1877. 
This  was  the  last  stand  of  his  opponents.  The  British 
Medical  Journal,  however,  heartily  urged  the  appoint- 
ment of  "the  great  surgeon  of  Edinburgh." 

October  i,  Lister  gave  his  first  lecture.  He  took  as  his 
subject  "Bacteriology,"  though  not  using  that  title  for, 
as  Stewart  said,  "as  yet  the  science  had  not  a  name."  ® 

Stewart  ^°  gives  a  vivid  account  of  the  dreary  days  dur- 
ing which  he  and  the  other  assistants  whom  Lister  had 
brought  with  him  from  Edinburgh  wandered  in  the  wards 
of  other  hospitals  "heavy  with  the  odor  of  suppuration" 
while  Lister's  own  small  wards  were  filled  with  empty 
beds.  Instead  of  the  Edinburgh  crowds  of  "500  eager 
listeners"  their  "hearts  were  chilled  by  the  listless  air  of 
the  12  or  20  students  who  lounged  into  lecture  at  King's" 
— only  12  or  20  students! 

But  a  month  later  the  tide  turned.^^  A  case  of  frac- 
tured patella  was  admitted  and  in  violation  of  all  surgical 
precedent,  for  in  that  septic  era  to  open  a  knee-joint  meant 
too  often  the  loss  of  limb  or  even  of  life,  Lister  boldly 

9  The  earliest  instance  of  the  use  of  the  word  "bacteriology" 
I  have  found  is  a  quotation  dated  1884  in  the  Oxford  Dictionary. 

10  Wrench,  p.  274  et  seq. 

11  Wrench,  p.  278  et  seq. 


BEFORE  AND  AFTER  LISTER  177 

opened  the  joint,  but  with  every  antiseptic  precaution, 
and  wired  the  two  fragments  together.  This  elicited  the 
remark  from  a  distinguished  London  surgeon : 

When  this  poor  fellow  dies,  some  one  ought  to 
proceed  against  that  man  for  mal-practice. 

But  the  man  got  well.  Soon  after  this  a  case  with  an 
enormous  malignant  tumor  of  the  thigh,  which  had  been 
declined  by  other  surgeons,  came  to  Lister.  He  amputated 
the  limb  and, 

the  members  of  the  staff  and  students  visiting  this 
interesting  patient  were  astonished  to  find  him  in  a 
day  or  two  sitting  up  in  bed  and  reading  a  paper,  be- 
ing free  from  pain  and  free  from  fever. 

A  little  later  Paget  and  Hewitt  both  refused  to  operate 
on  a  lady  of  social  importance  with  a  large  tumor  of  the 
shoulder-blade.  Lister  operated  in  the  presence  of  Paget 
and  Hewitt  and  she  recovered  without  suppuration,  fever 
or  pain. 

Yet  two  years  later  still  (1879)  Savory,  Thomas  Bry- 
ant, Tait  and  Spence,  while  claiming  to  practise  antiseptic 
surgery  so  far  as  strict  cleanliness  was  concerned,  declined 
to  subscribe  to  Lister's  doctrines  or  to  practise  his  method. 

But  the  enthusiastic  acclaim  of  the  International  Medi- 
cal Congress  in  Amsterdam  in  that  same  year  set  the  seal 
of  approval  of  the  profession  at  large.  This  may  be  said 
to  be  the  date  of  the  general  acceptance  of  Lister's  theory 
and  Lister's  method.    London  then  capitulated. 

In  1902,  twenty-three  years  later,  London  made  ample 
amends  for  its  persistent  early  skepticism  by  a  most  gen- 
erous outburst.  The  Royal  Society,  of  which  Lister  had 
been  president  and  from  which  he  had  received  two  med- 
als, gave  a  banquet  in  honor  of  the  jubilee  of  his  doctorate. 
It  was  a  most  distinguished  occasion  and  was  made  pre- 


178  CONTEMPORARY  SCIENCE 

eminent  by  a  most  happy  sentiment  by  Mr.  Bayard  the 
American  Ambassador.    Said  he,  addressing  Lister: 

My  Lord,  it  is  not  a  Profession,  it  is  not  a  Nation, 
it  is  Humanity  itself  which,  with  uncovered  head,  sa- 
lutes you. 

Better,  far  better,  such  a  eulogium  than  the  peerage 
which  had  been  already  bestowed  upon  him. 

Having  now  traced  so  imperfectly  the  fortunes  of  the 
germ  theory,  let  us  see  the  results  of  Lister's  labors.  The 
first  results  are  his  own,  especially  in  Glasgow.  There 
the  horrible  conditions  he  has  so  startlingly  portrayed  ^^ 
should  have  made  his  wards  a  charnel  house. 

The  mortality  in  the  other  accident  ward  was  so  ex- 
cessive that  it  had  to  be  closed.  But  in  Lister's  ward, 
separated  from  the  other  only  by  a  corridor  twelve  feet 
wide,  for  the  nine  months  "in  which  his  antiseptic  system 
had  been  fairly  in  operation  .  .  .  not  a  single  case  of 
pyemia,  erysipelas  or  hospital  gangrene  had  occurred." 

The  reason  for  his  first  attempt  to  apply  the  antiseptic 
system  to  man  is  well  stated  in  his  very  first  paper  on  the 
antiseptic  method  in  1867.^^    He  wrote: 

The  frequency  of  disastrous  consequences  in  com- 
pound fracture,  contrasted  with  the  complete  im- 
munity from  danger  to  life  or  limb  in  simple  fracture, 
is  one  of  the  most  striking  as  well  as  melancholy 
facts  in  surgical  practice. 

Well  might  he  say  this,  for  while  simple  fractures  had 
practically  no  mortality,  the  mortality  of  compound  frac- 
tures was  all  the  way  from  28  to  68  per  cent. !     In  this, 

12  Lancet,  1870,  I.,  pp.  4,  40,  and  quoted  in  my  Animal  Experi- 
mentation and  Medical  Progress,  pp.  216-218. 

^^  Lancet,  1867,  I.,  p.  326  et  seq.  and  II.,  p.  95,  and  Lister's 
Collected  Papers,  II.,  p.  1. 


BEFORE  AND  AFTER  LISTER  179 

his  first  paper,  he  reported  in  detail  eleven  cases,  with  one 
death,  an  unheard  of  mortality  of  only  9  per  cent. ! 

Thus  encourag-ed,  he  attacked  with  an  equally  happy 
outcome  abscesses,  especially  that  bane  of  surgery  in  those 
septic  days,  abscesses  of  the  spine.  Be  it  observed,  too, 
that  fifteen  long  years  were  to  elapse  before  the  tubercle 
bacillus,  the  cause  of  such  abscesses,  was  discovered  by 
Koch  (1882). 

From  accidental  wounds  it  was  but  a  step  to  deliberately 
inflicted  wounds,  i.e.,  surgical  operations.  Here,  too,  pre- 
ventive antisepsis  gave  equally  valuable  results. 

Lister,  however,  was  more  given  to  establishing  prin- 
ciples and  methods  than  to  statistics,  but  some  of  his  early 
disciples  published  striking  proofs  of  the  value  of  his 
method  by  contrasting  their  former  results  with  those 
which  followed  the  acceptance  of  the  germ  theory  and  the 
adoption  of  Lister's  antiseptic  treatment. 

Thus  Dennis^*  (1890)  says  that 

The  time  is  within  my  own  recollection  when,  in 
Bellevue  Hospital,  amputation  was  immediately  per- 
formed as  a  routine  treatment  to  prevent  blood  poison- 
ing, upon  the  admittance  of  a  compound  fracture ;  and 
this  operation  was  considered  by  surgeons  as  offering 
to  the  patient  the  only  chance  of  recovery. 

This  but  corroborates  what  Syme  had  already  said  in 
Edinburgh,  that  on  the  whole  he  was  inclined  to  think 

it  would  be  better  if  in  every  case  of  compound  frac- 
ture of  the  leg  amputation  were  done  without  any 
attempt  to  save  the  limb.^^ 

Dennis  in  his  paper  reported  681  cases  of  compound 
fracture,  with  only  19  deaths,  a  mortality  of  only  2.8 

1*  Medical  News,  April  19,  1890,  p.  423. 

15  Cameron,  Brit,  Med.  Jour.,  Dec.  13,  1902,  pp.  1844-1845. 


i8o  CONTEMPORARY  SCIENCE 

per  cent.,  and  only  one  of  these  19  deaths  was  from  sep- 
sis, or  1/7  of  I  per  cent. ! 

In  Nussbaum^s  insanitary  hospital  in  Munich,  which 
Lister  visited  in  the  summer  or  autumn  of  i375.  he 
states  ^^  that  pyemia  had  been 

very  frequent  and  hospital  gangrene  which  made  its 
appearance  in  1872,  had  become  annually  a  more  and 
more  frightful  scourge  until  in  1874  it  had  reached 
the  astounding  proportion  of  80  per  cent,  of  all 
wounds  that  occurred  in  the  hospital,  whether  acci- 
dental or  inflicted  by  the  surgeon ! 

After  trying  every  possible  different  method  of  treat- 
ment and  still  being  unable  to  combat  hospital  gangrene 
and  pyemia,  Nussbaum  finally  adopted  Lister's  full  anti- 
septic treatment  and  from  the  beginning  of  1875  they  had 
^'not  had  one  single  case  of  hospital  gangrene  .  .  .  and 
were  doubtful  whether  they  had  had  one  case  of  pyemia'' ; 
and 

the  convalescent  wards — which  previously  had  been 
filled  and  overflowing  constantly — Lister  saw  stand- 
ing one  after  another  empty,  because  patients,  no 
longer  affected  with  hospital  gangrene,  recovered 
much  more  rapidly. 

In  Halle  Volkmann  ^^  was  operating  in  an  extremely 
unhealthy  hospital  in  small,  overcrowded  wards,  with 
the  toilet  rooms  opening  directly  into  them  and  a  large 
drain  running  directly  underneath.  It  was  so  bad  that 
it  had  been  condemned  to  demolition.  In  the  two  years 
after  his  introduction  of  the  antiseptic  method  in  1872, 
no  single  patient  suffering  from  compound  fracture  had 
died  either  from  the  fracture  or  from  a  necessary  ampu- 

'^^Brtt.  Med.  Jour,,  1875,  IL,  p.  769,  and  Lister's  Works,  Vol. 
II.,  p.  248. 

T^"^  Lister's  Works,  IL,  pp.  249-251,  Brit,  Med,  Jour,,  1875,  II., 
p.  769,  and  Lindpainter  (Volkmann's  assistant),  Deutsch  Zeit,  f. 
Chir.,  Oct.,  1876,  p.  187. 


BEFORE  AND  AFTER  LISTER  i8i 

tation,  nor  was  there  a  single  death  from  secondary  hem-- 
orrhage  or  gangrene.  No  case  of  blood  poisoning  had 
occurred  for  a  year  and  a  half,  though  sixty  amputations 
had  been  done.  Just  before  Lister's  method  had  been 
introduced,  of  17  amputations  11  had  died  from  pyemia 
alone,  a  mortality  of  65  per  cent.  Just  after  adopting 
Listerism  the  death  rate  of  his  amputations  fell  to  4  or 
5  per  cent.^^ 

Hospital  gangrene  had  been  as  it  were  "blown  away*' 
by  a  puff  ("weggeblasen")  ;  not  a  single  case  occurred. 
In  Lindpainter's  extensive  tables  of  Nussbaum's  cases  one 
is  struck,  on  glancing  over  them,  to  see  how  before  the 
antiseptic  method  was  adopted  case  after  case  is  marked 
"died,"  "died,"  "died,"  and  in  the  later  tables,  after  its 
adoption,  almost  a  uniform  "recovered,"  "recovered,"  "re- 
covered." 

But  the  most  striking  testimony  to  the  value  of  Lister's 
services  to  suffering  humanity  is  not  the  statistics  of  the 
mortality  in  amputations,  compound  fractures,  puerperal 
fever  ^^  or  in  any  single  disease  or  operation,  but  in  the 
enormous  and  successful  enlargement  of  the  beneficent 
field  of  surgery.  In  my  own  early  days  "before  Lister" 
the  common  operations  were 

1.  Amputations. 

2.  Ligation  of  arteries. 

3.  Removal  of  external  tumors. 

4.  Lithotomy. 

5.  Tracheotomy,  chiefly  for  croup  and  foreign  bodies. 
A  few  resections,  colostomies,  trephining  (when  unavoid- 
able) and  herniotomies  (for  strangulation)  were  done. 
Ovariotomy  was  never  done  until  the  tumor  had  become 
so  large  as  to  threaten  life,  and  even  then  operation  was 
denounced  by  many  as  wholly  unjustifiable,  for  it  had  a 
mortality  as  high  as  two  out  of  every  three  cases.    The 

18  Lancet,  1881,  II.,  p.  281. 

1^  See  the  extraordinarily  interesting  paper  by  J.  Whitridgc 
Williams,  Jour.  Am.  Med.  Ass.,  April  33,  1911. 


i82  CONTEMPORARY  SCIENCE 

head,  the  chest,  the  abdomen  were  ticketed  ''Noli  me 
tangere"  except  in  the  rare  cases  when  operation  was 
absolutely  unavoidable. 

I  used  to  wonder  why  the  students  in  "Rab  and  His 
Friends"  rushed  to  the  amphitheater  to  get  the  best  seats 
to  see  Syme  amputate  a  breast — a  so  very  common  oper- 
ation nowadays.  But  then  I  recalled  the  fact  that  even 
in  my  student  days,  when  anesthesia  was  the  rule,  capital 
operations  were  rare.  But  in  the  pre-anesthetic  days  op- 
erations were  far  rarer.  In  the  five  years  preceding  the 
introduction  of  ether  at  the  Massachusetts  General  Hos- 
pital the  entire  staff  only  performed  in  all  184  operations 
or  three  operations  a  month.  When  operations  had  be- 
come not  only  painless,  but  safe,  then  the  number  per- 
formed increased  almost  at  a  geometrical  ratio,  so  that  at 
present  the  numbers  even  of  single  operations  by  single 
surgeons — e.g.,  of  ovariotomies,  appendectomies,  goiters 
— mount  Into  the  thousands.  What  is  still  more  gratify- 
ing, the  usual  death  rates  of  most  capital  operations  in  the 
pre-Listerian  days  of  one  patient  in  four,  in  three,  or  in 
two,  or  even  two  out  of  three  (  !)  have  been  changed  to 
one  in  twenty,  thirty,  fifty,  or  to  even  less  than  one  life 
lost  in  one  hundred  or  even  one  in  two  hundred  opera- 
tions ! 

It  is  impressive — most  impressive — to  call  the  list  of 
only  the  most  frequent  and  the  most  important  of  our 
present  operations.  Were  Mott,  Bigelow  or  Pancoast — 
all  of  whom  I  remember  well — to  come  to  life  again  they 
would  wonder  whether  we  were  not  stark  crazy. 

The  following  list  I  have  made — ciirrente  calamo — on 
the  instant. 

Amputations  are  far  less  frequent.  After  a  single  bat- 
tle in  the  Russian  campaign  (1812),  Larrey,  Napoleon's 
great  surgeon,  performed  not  less  than  200  amputations. 
To-day  of  200  similar  cases,  sometimes  even  with  wounds 
involving  joints,  the  great  majority  would  recover  with- 
out amputation. 


BEFORE  AND  AFTER  LISTER  183 

Formal  ligations  are  far  fewer. 

External  tumors  of  any  size  are  now  removed  from 
all  parts  of  the  body  without  fear  of  erysipelas,  which  so 
worried  Sir  Astley  Cooper  before  he  operated  on  the  king 
for  a  simple  wen.  The  mere  fact  that  any  tumor  is  in- 
ternal— inside  the  head,  the  chest,  the  abdomen,  or  the 
pelvis — has  practically  no  influence  on  the  decision 
whether  it  should  or  should  not  be  removed. 

Trephining — even  for  exploration — is  frequent  and  per 
se  involves  slight  danger,  as  in  decompression. 

Martin,  of  Berlin,  has  done  over  1,000  ovariotomies, 
with  a  mortality  of  less  than  2  per  cent.,  and  the  Mayos 
from  1905  to  1914,  inclusive  (the  only  period  for  which 
I  had  the  annual  reports  at  hand),  reported  609  cases 
with  5  deaths,  or  eight-tenths  of  i  per  cent.  Colostomy 
and  enterostomy  are  frequent.  Many  thousands  of  her- 
nias have  been  cured  by  operation,  with  practically  no 
mortality;  and  if  done  early  in  strangulation,  with  slight 
mortality. 

The  new  surgery  of  the  head  attacks  tumors  even  of 
the  hypophysis,  punctures  the  lateral  and  the  fourth  ven- 
tricles with  impunity,  successfully  extracts  foreign  bodies 
and  in  some  cases  relieves  epilepsy  and  mental  derange- 
ments. 

In  the  neck  simple  goiters  even  of  large  size  are  re- 
moved, with  a  mortality  of  i  and  2  per  cent. ;  and  laryn- 
gectomy is  common. 

In  the  chest,  that  very  citadel  of  life,  the  heart  itself 
is  sutured  for  gunshot  and  stab  wounds,  saving  one  life 
out  of  two ;  the  esophagus  is  attacked  for  cancer  and  the 
removal  of  foreign  bodies ;  large  portions  of  the  chest 
wall  are  removed  for  old  empyemas,  and  the  lungs  can 
now  be  operated  on  at  leisure,  thanks  to  insufflation  anes- 
thesia. 

In  the  abdomen,  the  various  operations  on  the  stomach, 
even  to  its  total  extirpation,  are  too  many  to  name  in 
detail;  and  with  a  success  that  is  truly  marvellous.    We 


i84  CONTEMPORARY  SCIENCE 

play  with  the  intestines  at  will,  opening  them  for  foreign 
bodies  and  for  drainage  of  the  contents,  removing  what 
we  wish,  anastomosing  them  and  short  circuiting  their 
contents.  Tumors  of  the  liver  unless  malignant  are  ex- 
tirpated with  a  very  low  mortality  and  wounds  of  its 
substance  are  treated  with  success;  gall  stones  and  gall 
bladders  are  removed  every  day;  the  spleen  is  anchored, 
sutured  or  removed  as  we  find  best;  the  pancreas  is  no 
longer  inaccessible;  the  kidney  and  the  ureter,  like  the 
stomach,  have  their  own  lists  of  operations  far  too  long 
to  rehearse. 

In  the  pelvis  the  bladder  is  opened  and  partly  or  even 
wholly  extirpated ;  the  prostate  removed ;  the  uterus,  the 
ovary,  the  tubes,  the  parovaria  have  a  long  list  of  life- 
saving,  comfort-giving  operations  to  their  credit. 

We  suture  and  anastomose  nerves ;  we  suture  and  anas- 
tomose blood  vessels  even  in  the  new-born,  we  criss-cross 
the  circulating  blood  to  prevent  gangrene,  and  endo- 
aneurismorrhaphy  has  practically  banished  the  Hunterian 
operation  for  aneurism  and  saved  many  a  limb  and  life. 
We  transplant  skin  and  bones  and  joints,  and  even  half 
joints,  with  success.  To  all  these  we  have  added  the 
X-rays,  the  serum  and  vaccine  treatment  of  many  surgi- 
cal disorders  and  are  gradually  throttling  disease,  some- 
times at  its  very  birth. 

It  almost  takes  one's  breath  away !  Yet  it  is  an  incom- 
plete and  ever-lengthening  list !  As  Mumf ord  ^^  well 
says : 

Daring  has  become  conservatism ;  rashness  has  be- 
come common  sense. 

Practically  our  ability  to  do  all  these  life-sainng  opera- 
tions is  the  result  of  the  researches,  the  experiments,  and 
the  achievements  of  Lister  and  his  followers.  Had  anti- 
sepsis not  made  all  operations,  including  the  opening  of 
the  head,  the  chest,  the  abdomen,  and  the  pelvis,  safe,  we 

'^^  Keen's  Surgery,  I.,  p.  76. 


BEFORE  AND  AFTER  LISTER  185 

should  still  be  practising  the  very  limited  surgery  of  the 
6o's.  Every  year  thousands  whom  now  we  restore  to  life 
and  health  would  still  be  dying. 

What  now  are  the  prospects  of  Listerism  in  the  present 
horrible  war?  I  have  so  far  used  the  term  "antisepsis." 
Asepsis  is  a  later  and  a  natural  development  of  antisepsis 
and  in  civil  life  is,  of  course,  preferable.  The  under- 
lying and  enduring  principle  of  Listerism — the  germ  theory 
— ^is  the  same  in  both.  There  is  no  fundamental  antago- 
nism, but  really  a  fundamental  agreement  between  the  two 
methods. 

In  the  present  war  the  surgeons  whose  papers  I  have  so 
far  read  are  almost  a  unit  in  favor  of  the  antiseptic  rather 
than  the  aseptic  treatment  of  the  wounded.  They  are 
right  in  my  opinion,  and  the  reason  is  plain.  Compara- 
tively few  of  the  wounded  reach  hospitals  with  uninfected 
wounds.  Mild  wounds,  and  even  in  some  cases  severe 
ones,  if  they  can  be  dressed  soon  after  being  inflicted, 
heal  readily. 

Sir  Anthony  Bowlby's  ^^  striking  description  of  the  con- 
ditions in  the  trenches  shows  the  difficulties  very  clearly: 

In  this  trench  warfare,  if  a  man  is  hit,  he  often 
falls  into  filthy  mud  and  water,  which  may  be  three 
feet  deep  or  more.  The  trench  is  only  two  and  a 
half  feet  wide.  It  is  night,  you  can  only  grope  about 
in  the  dark  and  can  do  no  dressing  of  any  kind,  for 
you  can't  even  get  any  clothes  off  in  the  dark,  and 
in  so  cramped  a  space,  and  you  must  try  to  get  the 
man  away  to  a  "dressing  station"  half  a  mile  distant, 
and  thence  to  a  field  ambulance.  If  it  is  daylight, 
you  can't  get  the  man  out  of  the  trench  at  all,  and 
he  may  have  to  be  kept  there  for  many  hours,  because 
he  would  certainly  be  killed  if  he  were  got  out  of  the 
trench.  And  the  water  in  the  trenches  is  hopelessly 
polluted  and  soaks  his  clothes  and  his  wound.  Large 
21/ottr.  Am,  Med,  Ass.,  April  10,  1915,  p.  1257. 


i86  CONTEMPORARY  SCIENCE 

lacerated  wounds,  and  especially  bad  bone  smashes, 
are  so  contaminated  that  it  can  never  be  possible  to 
render  them  aseptic. 

There  is  a  noteworthy  difference  between  the  results 
of  the  wounds  in  the  case  of  the  trench-inhabiting  soldiers 
and  the  wounds  of  sailors.  The  latter  escape  the  dangers 
of  the  soil-infected  trenches. 

Sailors  with  the  most  severe  type  of  wound,  ragged, 
irregular,  with  uneven  surface  produced  by  herniated 
muscle  and  retracted  severed  fibers,  usually  have  re- 
covered promptly.  Soldiers  suffering  from  slight 
wounds  have  often  had  them  contaminated  with  bac- 
illi from  the  soil ;  particularly  the  anaerobes. 

Hypertonic  salt  solutions  like  sea  water  are  actually 
remedial  by  promoting  the  flow  of  lymph  and  serum  in 
the  wounded  tissues. 

But  in  a  very  large  number  of  wounded  soldiers,  pos- 
sibly the  majority,  hours  and  sometimes  even  days  of 
delay  ensure  infection  and  then  the  surgeon  is  face  to  face 
with  the  one  overwhelming  surgical  problem  which  has 
so  far  baffled  all  our  efforts,  7A2.,  how  to  transform  a  sep- 
tic wound  into  an  aseptic  wound  and  keep  it  so,  and  at 
the  same  time  how  to  combat  the  toxins  already  diffused 
throughout  the  body,  but  without  doing  harm  to  the  pa- 
tient himself.  Cheyne,^^  Ehrlich,  Wright  and  Carrel  are 
all  at  work  and  it  may  be  that  the  happy  day  when  this, 
the  most  pressing  and  urgent  problem  in  surgery,  shall  be 
solved,  may  come  through  this  devastating  war.^^ 

22  Lancet,  Feb.  27,  1915,  p.  419. 

23  In  the  British  Medical  Journal  of  April  10,  1915,  a  most  im- 
portant article  by  Sir  Almoth  E.  Wright  on  "Wound  Infections" 
is  begun.  This  should  be  very  carefully  read.  On  pp.  735-738 
of  the  same  Journal  for  April  24,  1915,  is  another  very  important 
paper  giving  full  directions  for  treatment.  See  also  an  interesting 
editorial  in  the  Journal  American  Medical  Association,  May  23, 
1915,  p.  1765. 


BEFORE  AND  AFTER  LISTER  187 

Meantime  Souttar  ^^  extols  plenty  of  fresh  air  or  bet- 
ter still  of  oxygen  (our  old  supposed  enemies  in  the  6o's) 
and  says : 

Men  with  wounds  so  foul  that  their  presence  in  the 
wards  could  not  be  permitted,  were  placed,  suitably 
protected,  in  the  open  air,  the  wounds  being  left  ex- 
posed to  the  winds  of  heaven,  covered  only  with  a 
thin  piece  of  gauze.  The  results  were  almost  magi- 
cal, for  in  two  or  three  days  the  wounds  lost  their 
odor  and  began  to  look  clean,  while  the  patient  lost 
all  signs  of  the  poisoning  which  had  been  so  marked 
before. 

Of  tetanus  in  our  Civil  War  there  were  in  the  Union 
army  in  all  505  cases  and  451  deaths,  89.3  per  cent.  In 
the  War  of  1870 — i  in  the  German  army  there  were  294 
cases  and  268  deaths,  or  91.  i  per  cent.  In  the  present 
war  there  have  been  many  cases  in  the  allied  armies  in 
the  west,  but  I  have  seen  no  numbers  or  percentages.  In 
the  German  army,  however,  Czerny  ^^  says  that 

the  greatest  danger  to  the  wounded  had  been  tetanus. 
Of  60,000  wounded  Bavarians,  420  developed  tetanus, 
which  proved  fatal  in  240  cases  (57.1  per  cent.) .  The 
prophylactic  value  of  the  tetanus  serum  had  been 
established,  but  its  extensive  employment  was  not 
always  feasible. 

This  is  a  far  larger  percentage  of  cases  than  in  our 
Civil  War,  or  the  Franco-Prussian  War,  but  the  mortality 
is  far  less — probably  due  to  the  even  partial  employment 
of  the  serum. 

During  the  Civil  War  I  never  saw  a  case  of  "gas  gan- 
grene" which  has  been  so  prevalent  and  dangerous  in 

24Bnf.  Med.  Jour.,  March  20,  1915,  p.  504. 
25  Brit.  Med.  Jour.,  March  20,  1915,  p.  521. 


i88  CONTEMPORARY  SCIENCE 

the  present  war.  The  soil  of  Belgium  and  France,  which 
has  been  cultivated  and  roamed  over  by  animals  for  more 
than  twenty  centuries,  is  highly  infected.  Over  ten  dif- 
ferent gas-producing  bacteria  have  been  found. 

Sidney  Rowland's  experiment  ^^  well  shows  the  viru- 
lent infection  of  the  soil.  Shaking  up  some  of  the  soil 
from  the  trenches  with  some  water,  he  injected  a  few 
drops  into  a  guinea-pig  and  it  was  dead  in  eighteen  hours 
with  widely  diffused  gas  gangrene.  Soldiers  h^ve  died 
from  the  disease  in  thirty-six  hours. 

Delorme  has  advised,  as  the  germ  is  anaerobic,  the  in- 
jection of  peroxide  of  hydrogen.  Hartmann  believes  it 
needful  to  open  the  wounds  freely  and  employ  thorough 
irrigation  with  the  peroxide  ^* — a  most  important  pro- 
cedure. Early  treatment  of  infected  wounds  even  in  cases 
of  gas  gangrene  resulted  favorably  in  the  hands  of  Cazin. 
Of  158  cases  received  even  up  to  forty-eight  hours  after 
battle  all  recovered  in  spite  of  their  serious  nature.  Among 
those  received  after  four  or  five  days'  transportation  the 
mortality  reached  10  and  even  20  per  cent.^^ 

I  have  related  the  terrible  mortality  from  typhoid  in 
the  Boer  and  the  Spanish-American  wars.  The  one  bright 
spot  in  the  present  war  is  the  conquest  of  typhoid.  In 
spite  of  greatly  increased  numbers  and  of  most  unfavor- 
able sanitary  conditions  in  the  trenches  as  I  have  shown, 
conditions  which  in  former  wars  would  have  given  rise  to 
dreadful  epidemics  of  typhoid,  the  following  statistics  in 
the  British  army  officially  given  to  Parliament  on  March 
4,  1915,^^  show  emphatically  how  well  this  scourge  of 
every  past  campaign  has  been  conquered.  There  had 
been  only  606  cases  in  all :  247  among  the  partially  (136) 
and  fully   (m)    inoculated,  with  two  deaths   (0.81  per 

26Pn7.  Med.  Jour.,  Nov.  28,  1914,  p.  913. 

27/owr.  Am.  Med.  Ass.,  Jan.  16,  1915,  p.  259.     See  also  Law- 
son  and  Whitehouse,  Brit.  Jour.  Surg.,  Jan.  9,  1915,  p.  444. 
28/oMr.  Am.  Med.  Ass.,  Jan.  16,  1915,  p.  259. 
29  Brit.  Med.  Jour.,  March  13,  1915,  p.  485. 


BEFORE  AND  AFTER  LISTER  189 

cent.),  and  359  among  the  unprotected,  with  48  deaths 
(7.47  per  cent.),  over  nine  times  as  many  deaths  pro- 
portionately! The  one  reason  for  this  splendid  showing 
is  the  use  of  the  antityphoid  inoculation.  If  instead  of  its 
being  only  voluntary  in  the  British  army  it  had  been  com- 
pulsory as  in  our  own  army,  the  results  would  have  been 
even  better.  And  yet  a  blatant  band  of  men  and  women 
both  in  England  and  our  own  country  are  doing  all  they 
can  to  oppose  the  use  of  this  life-preserving  remedy! 

Let  us  now  in  conclusion  take  a  general  review  of  the 
surgical  progress  I  have  so  inadequately  sketched. 

During  the  horrible  days  of  Pare,  Bell,  Simpson,  and 
our  own  Civil  War  there  was  still  gradual  improvement, 
but  no  fundamental  change  occurred  for  three  centuries 
after  Pare  introduced  the  ligature  and  banished  the  boil- 
ing oil. 

But  about  the  middle  of  the  nineteenth  century,  and 
especially  in  its  last  quarter,  experimental  research  took 
the  field.  Everything  that  could  be  put  to  the  test  of 
accurate  experiment  in  medicine  and  surgery  was  thor- 
oughly investigated  physically,  physiologically,  chemically, 
microscopically,  biologically,  bacteriologically.  Labora- 
tories were  founded  and  research  workers  vied  with  each 
other  in  countless  investigations.  A  flood  of  light  was 
thrown  upon  every  problem.  And  see  the  result  in  the 
long  list  I  have  just  read  to  you!  Medicine  proper,  ob- 
stetrics, all  the  specialties,  sanitation  and  hygiene,  furnish 
equally  impressive  calendars  of  progress — ^principally  the 
result  of  experimental  research. 

Chief  among  these  experimental  researches  were  those 
of  Pasteur  (of  whom  I  have  said  far  too  little  for  want 
of  time)  and  of  Lister.  They  inaugurated  a  wholly  new 
era  in  surgery. 

Then  followed  the  battle  for  the  germ  theory  and  anti- 
septic surgery,  ending  in  final  victory.  Meantime  a  new 
science,  bacteriology,  was  born. 

Next  came  the  wide  extension  and  application  of  the 


t9o  CONTEMPORARY  SCIENCE 

new  surgery  to  almost  all  the  surgical  ills  that  flesh  is 
heir  to.  The  wonderful  results  to  both  life  and  limb  that 
I  have  recounted  have  naturally  followed. 

Even  amid  the  disabilities  and  obstacles  of  war  itself 
Lister's  work  has  been  a  boon  beyond  price. 

While  the  soldier  and  the  scientist  have  been  busy  de- 
vising ever  more  frightful  engines  of  destruction  to  maim 
und  to  kill,  we  surgeons  have  been  equally  busy  devising 
means  for  saving  thousands  of  lives  and  limbs  in  civil 
life,  and  even  amid  the  carnage  and  savagery  of  war. 

Surely  our  hearts  should  be  lifted  in  gratitude  to  God 
for  giving  us  such  splendid  powers  of  reasoning,  experi- 
ment and  research — all  for  the  service  of  our  fellow  men. 

In  the  five  years  since  these  lectures  were  delivered,  the 
treatment  of  infected  wounds  has  been  revolutionized,  and 
with  the  happiest  results.  The  exact  percentages  have 
not  yet  been  tabulated. 

If  seen  within  about  the  first  twenty-four  hours  after 
the  wound  has  been  inflicted,  the  wounds  were  usually 
only  "contaminated" ;  i.e.,  the  germs  had  only  invaded  the 
surface  and  had  penetrated  to  a  slight  depth  into  the  tis- 
sues. In  this  case,  careful  removal  of  all  "foreign  bodies," 
such  as  fragments  of  the  missile,  and  especially  of  in- 
fected clothing  carried  deep  into  the  wound,  was  thor- 
oughly carried  out.  The  wound  was  then  widely  opened 
down  to  the  very  bottom  (debridement).  This  was 
followed  by  the  entire  removal  of  the  layer  of  "contami- 
nated" flesh  to  which  as  yet  the  bacteria  were  practically 
confined  (epluchage).  By  these  steps,  the  great  bulk  of 
the  germs  were  removed  mechanically.  Moreover,  this 
contaminated  layer  of  tissue,  owing  to  the  injury  done  to 
it  by  the  missile  moving  with  enormous  velocity,  had  had 
its  vitality  destroyed  and  was  sure  to  die.  Such  dead  and 
dying  tissue  was  the  most  favorable  food  for  the  bac- 
teria. 

The  wound  could  then  be  closed  at  once  and  immediate 
recovery,  without  fever  or  suppuration,  followed  in  eighty 


BEFORE  AND  AFTER  LISTER  191 

or  ninety  per  cent,  or  even  a  larger  percentage  of  the 
cases!    The  knife  was  the  best  "antiseptic." 

In  cases,  in  which  by  delay,  the  bacteria  had  invaded  the 
tissues  more  deeply,  debridement  and  epluchage  alone 
were  not  sufficient.  Then  chemical  disinfection,  chiefly 
by  the  method  of  Carrel  and  Dakin,  was  employed.  After 
a  few  days,  or  sometimes  a  few  weeks,  the  bacteria  would 
be  destroyed  and  then  the  wound  could  be  closed  with 
success.  The  chemical  used  was  bleaching  powder  or 
Sulfite  of  Soda  in  a  weak  solution.  This  fluid  was  dis- 
tributed to  every  part  of  the  wound  by  small  rubber  tubes, 
closed  at  the  far  end  but  with  many  small  holes  in  the 
sides.  By  these  means,  the  infected  wound  was  kept 
constantly  bathed  in  the  antiseptic  fluid  and  the  germs 
were  gradually  destroyed. 

Lister's  fundamental  postulate — ridding  the  wounds  of 
bacteria — whether  mechanically  by  the  knife,  or  chemi- 
cally by  destroying  them — ^was  more  firmly  established 
than  ever  before. 

When  the  Surgical  History  of  the  War  is  published,, 
the  wonderful  results  in  saving  life  will  be  an  astonishing: 
story. 


THE  MEASUREMENT  AND  UTILIZATION 
OF  BRAIN   POWER   IN   THE  ARMY 

BY 

R.  M.  Yerkes 

Chief,  Section  of  Psychology,  Office  of  the 

Surgeon-General 

History  of  Psychological  Service. — The  psychologists 
of  America,  of  whom  upward  of  two  hundred  served  in 
the  Army  or  Navy,  have  rendered  conspicuously  impor- 
tant assistance  to  the  government  in  organizing  an  efficient 
fighting  machine.  Chief  among  the  civilian  agencies  re- 
sponsible for  the  development  of  this  new  and  unexpect- 
edly significant  variety  of  service  are  the  American  Psy- 
chological Association  and  the  Psychology  Committee  of 
the  National  Research  Council.  Nearly  a  score  of  com- 
mittees or  subcommittees  of  these  organizations  functioned 
during  the  military  emergency. 

Within  the  Army  three  principal  groups  of  psycholo- 
gists appear:  one  attached  to  the  Office  of  the  Adjutant 
General  of  the  Army  (specifically  known  as  the  Commit- 
tee on  Classification  of  Personnel  in  the  Army),  another 
in  the  Office  of  the  Surgeon  General  of  the  Army  (known 
as  the  Division  of  Psychology  of  the  Medical  Depart- 
ment), and  a  third  in  the  Division  of  Military  Aeronautics 
(the  Psychological  Section  of  the  Medical  Research 
Board).  Although  the  several  tasks  of  these  groups  of 
psychologists  differed  markedly,  the  primary  purpose  of 
each  was  the  increase  of  military  efficiency  through  im- 

192 


UTILIZATION  OF  BRAIN  POWER  IN  ARMY    193 

proved  placement  with  respect  alike  to  occupational  and 
mental  classifications. 

Psychological  service  was  rendered  also  to  the  follow- 
ing divisions  or  departments  in  addition  to  those  named 
above:  (i)  the  Morale  Branch  of  the  General  Staff,  (2) 
the  Division  of  Military  Intelligence,  (3)  the  Committee 
on  Education  and  Special  Training  of  the  War  Depart- 
ment, and  (4)  the  Chemical  Warfare  Service.^ 

Early  in  the  emergency  it  became  clear  to  psychologists, 
in  the  military  service  that  the  fundamental  psychological 
problem  of  the  army  is  one  of  placement  and  that  the 
most  important  service  psychologists  could  possibly  render 
would  be  to  assist  in  so  assigning  every  soldier  that  his 
mental  (as  well  as  physical)  ability  should  be  used  to  ad- 
vantage. It  was  assumed  by  the  psychological  personnel 
that  intelligence,  alertness  the  will  to  win,  enthusiasm, 
faith,  courage  and  leadership  are  even  more  important 
than  are  physical  strength  and  endurance,  and  that  this 
fact  must  be  scientifically  reckoned  with  wherever  a 
strong  military  organization  is  to  be  built  quickly.  Very 
promptly  it  became  the  recognized  purpose  of  army  psy- 
chologists to  assist  in  winning  the  war  by  the  scientific 
utilization  of  brain  power.  The  achievement  of  this  pur- 
pose necessitated  the  preparation  of  special  methods  of 
mental  measurement  in  order  that  recruits  should  be  prop- 
erly classified  for  elimination  or  assignment  to  military 
training. 

The  army,  at  first  naturally  and  wisely  skeptical  con- 
cerning the  practical  values  of  psychological  service  and 

^  For  the  United  States  Navy  serviceable  methods  of  selecting, 
placing  and  training  gunners,  listeners  and  lookouts  were  devised 
and  developed  by  Lieutenant  Commander  Raymond  Dodge.  The 
methods  prepared  by  Dr.  Dodge  as  well  as  certain  instruments 
designed  by  him  for  naval  use  have  been  extensively  and  profit- 
ably used,  and  the  appointment  of  this  psychologist  as  Lieutenant 
Commander  in  the  Naval  Reserve  is  at  once  a  fitting  recognition 
of  his  practical  service  and  an  indication  of  the  appreciation  of 
his  work  by  the  officers  with  whom  he  has  been  associated. 


194  CONTEMPORARY  SCIENCE 

inclined  to  anticipate  research  instead  of  service,  shortly 
achieved  a  new  point  of  view  and  opinion.  Skepticism 
was  replaced  in  some  directions  gradually,  elsewhere  rap- 
idly, by  faith  in  the  practicability  and  immediate  value 
of  various  kinds  of  psychological  work  and  eagerness  for 
its  continuation  and  extension.  In  the  end  the  psycho- 
logical personnel  of  the  army  was  completely  swamped  by 
requests,  demands  and  orders  for  help.  Scores  of  tele- 
grams and  letters  from  commanding  officers  testify  to 
their  hearty  appreciation  of  efforts  towards  scientific 
placement  within  the  army  and  their  desire  for  the  in- 
troduction or  furtherance  of  psychological  service  in  va- 
rious departments  or  organizations. 

Skeptics,  of  course,  still  exist  and  there  are  inevitable 
misunderstandings  and  prejudices,  but  the  data  at  hand 
indicate  that  at  least  seventy-five  per  cent,  of  the  officers 
of  the  United  States  Army  have  been  won  by  actual  dem- 
onstration of  values  and  first  hand  acquaintance  with 
psychological  service  to  its  hearty  support. 

It  is  extremely  important  to  emphasize  at  the  outset 
that  this  article  deals  with  only  one  of  the  several  impor- 
tant lines  of  psychological  military  service,  that,  namely, 
of  the  Division  of  Psychology  of  the  Medical  Depart- 
ment. 

Purposes  of  Mental  Examining, — As  originally  con- 
ceived, psychological  service  within  the  Medical  Depart- 
ment was  to  assist  medical  officers,  and  especially  neuro- 
psychiatric  officers,  in  discovering  and  eliminating  men 
who  are  mentally  unfit  for  military  duty.  It  appeared, 
prior  to  actual  trial,  that  reasonably  well  planned  methods 
of  mental  measurement  should  enable  psychological  exam- 
iners to  discover  mentally  inferior  recruits  as  soon  as 
they  arrived  in  camp  and  to  make  suitable  recommendation 
concerning  them  to  the  medical  officer.  It  was  also  be- 
lieved that  psychologists  could  assist  neuro-psychiatrists 
in  the  examination  of  psychotic  individuals.  The  pro- 
posed role  of  the  psychologist  then  was  that  of  assistant 


UTILIZATION  OF  BRAIN  POWER  IN  ARMY    195 

to  the  army  surgeon :  the  actual  role,  as  a  result  of  dem- 
onstration of  values,  was  that  of  expert  in  scientific  per* 
sonnel  work. 

In  interesting  contrast  with  the  original  purpose  of 
mental  examining,  as  stated  above,  stands  the  following 
account  of  the  purposes  actually  achieved  by  this  service : 
(i)  The  assignment  of  an  intelligence  rating  to  every 
soldier  on  the  basis  of  systematic  examination;  (2)  the 
designation  and  selection  of  men  whose  superior  intelli- 
gence indicates  the  desirability  of  advancement  or  special 
assignment;  (3)  the  prompt  selection  and  recommenda- 
tion  for  development  battalions  of  men  who  are  so  in- 
inferior  mentally  as  to  be  unsuitable  for  regular  military 
training;  (4)  the  provision  of  measurements  of  mental 
ability  which  shall  enable  assigning  officers  to  build  or- 
ganizations of  uniform  mental  strength  or  in  accordance 
with  definite  specifications  concerning  intelligence  require- 
ments; (5)  the  selection  of  men  for  various  types  of  mili- 
tary duty  or  for  special  assignments,  as  for  example,  to 
military  training  schools,  colleges  or  technical  schools; 
(6)  the  provision  of  data  for  the  formation  of  special 
training  groups  within  the  regiment  or  battery  in  order 
that  each  man  may  receive  instruction  suited  to  his  ability 
to  learn ;  (7)  the  early  discovery  and  recommendation  for 
elimination  of  men  whose  intelligence  is  so  inferior  that 
they  cannot  be  used  to  advantage  in  any  line  of  military 
service. 

Although  it  originally  seemed  that  psychological  ex- 
amining naturally  belonged  in  the  Medical  Department  of 
the  Army  and  would  there  prove  most  useful,  it  subse^ 
quently  became  evident  that  this  is  not  true  because  the 
service  rendered  by  psychological  examiners  is  only  in 
part  medical  in  its  relations  and  values.  In  the  main  its 
significance  relates  to  placement  and  its  natural  affiliation 
is  with  military  personnel.  For  practical  as  well  as  logi- 
cal reasons  it  would  doubtless  have  been  wiser  had  the 
service  of  the  Division  of  Psychology  been  associated 


196  CONTEMPORARY*  SCIENCE 

from  the  first  with  that  of  the  Committee  on  Qassifica- 
tion  of  Personnel  in  the  Army,  so  that  the  psychological 
as  well  as  occupational,  educational  and  other  important 
data  might  have  been  assembled  by  a  single  military  agency 
and  promptly  rendered  available  for  use  in  connection 
with  the  assignment  of  recruits.  Thus  also  the  organiza- 
tion of  a  special  branch  of  the  General  Staff  or  of  a  Per- 
sonnel Section  of  the  Adjutant  General's  Office  to  deal 
with  varied  problems  of  military  personnel  might  have 
been  hastened  and  otherwise  facilitated  and  the  utilization 
of  brain  power  as  contrasted  with  man  power  in  the  ordi- 
nary sense  rendered  more  satisfactory  early  in  the  emer- 
gency. 

Methods  of  Measuring  Intelligence. — The  committee 
of  psychologists  originally  organized  to  prepare  and  test 
methods  of  psychological  examining  for  the  army 
promptly  decided  that  it  would  be  desirable  to  examine  all 
recruits  in  order  to  provide  an  intelligence  rating  fcr 
every  soldier.  This  decision  necessitated  the  development 
of  methods  which  could  be  administered  to  relatively  large 
groups  and  in  addition  the  selection  of  procedures  which 
could  be  used  for  the  more  careful  examination  of  in- 
dividuals. 

Most  of  the  methods  which  were  recommended  to  the 
military  authorities  in  the  summer  of  191 7  have  since 
that  time  been  repeatedly  revised  and  improved  in  the 
light  of  results.  The  procedures  finally  adopted  and  in 
use  throughout  the  army  during  the  past  few  months 
dififer  radically  from  those  originally  recommended.  They 
may  be  described  summarily  as  follows : 

There  are  four  principal  systems  or  stages  in  the  ex- 
amination. First  comes  the  procedure  of  segregation,  by 
means  of  which  the  original  group,  which  may,  if  exam- 
ining rooms  permit,  include  as  many  as  five  hundred 
men,  is  split  into  two  sub-groups;  (a)  the  literates,  men 
who  can  speak  and  read  English  fairly  well,  and  {h)  the 
Illiterates,  men  who  are  relatively  unfamiliar  with  the 


UTILIZATION  OF  BRAIN  POWER  IN  ARMY    197 

English  language.  These  two  groups  must  necessarily  be 
treated  somewhat  differently,  therefore  the  literates  are 
given  a  group  examination  known  as  Alpha,  which  con- 
sists of  eight  markedly  different  tests.  This  examination, 
although  it  requires  almost  no  writing  on  the  part  of  the 
subject,  does  demand  facility  in  using  written  and  oral 
instructions.  The  illiterate  group  is  given  an  examination 
known  as  Beta,  which  is  in  effect  Alpha  translated  into 
pictorial  form.  In  this  examination  pantomime  and  dem- 
onstration supplant  written  and  oral  instructions. 

Each  group  examination  requires  approximately  fifty 
minutes.  Subjects  who  fail  in  Alpha  are  ordinarily  given 
opportunity  to  improve  their  ratings  by  taking  Beta,  and 
subjects  who  fail  in  Beta  are  given  individual  examina- 
tion in  order  that  they  may  be  more  accurately  and  justly 
rated  than  in  the  group  examination  alone. 

Any  particular  individual  may  have  to  take  one,  two  or 
three  of  these  types  of  examination,  thus  for  example,  a 
man  of  low  grade  literacy  who  happens  to  get  into  exami- 
nation Alpha  may  also  have  to  take  Beta  and  some  form 
of  individual  examination. 

Examination  papers  for  both  Alpha  and  Beta  are  scored 
rapidly  by  the  use  of  stencils  and  the  resulting  rating 
is  promptly  reported  to  the  appropriate  military  au- 
thority. 

By  means  of  this  system  of  examinations  it  is  possible 
for  an  examining  staff  consisting  of  four  psychologists 
and  a  force  of  scoring  clerks  to  examine  as  many  as  one 
thousand  men  per  day. 

Every  man  examined  by  one  or  more  of  the  procedures 
described  is  assigned  a  numerical  rating  and  in  addition 
a  letter  grade  which  indicate  his  general  intellectual  abil- 
ity or  mental  alertness.  The  numerical  rating  is  used 
only  for  statistical  purposes,  the  letter  grade  for  practical 
military  purposes.  The  latter  alone  is  reported  ordinarily 
to  military  officers  and  recorded  on  the  soldier's  service 
record  and  qualification  card. 


198  CONTEMPORARY  SCIENCE 

The  letter  grades  which  are  in  use  are  defined  as  fol- 
lows :  A  designates  very  superior  intelligence ;  B,  superior 
intelligence;  C +»  high  average  intelligence;  C,  average 
intelligence;  C — ,  low  average  intelligence;  D,  inferior 
intelligence;  D — ,  very  inferior  intelligence.  The  letter 
E  has  been  reserved  for  the  designation  of  men  whose 
mental  ability  is  seemingly  inadequate  for  regular  military 
duty. 

Commissioned  officers  usually  possess  and  obviously 
should  possess  A  or  B  intelligence.  Many  excellent  non- 
commissioned officers  possess  C  or  C  +  intelligence,  but  in 
the  main  this  group  is  composed  of  men  with  C+  or  B 
ratings.  The  great  body  of  privates  grades  C.  Men  with 
D  or  D  —  intelligence  are  usually  slow  to  learn  and  rarely 
gain  promotion.  Many  of  them,  especially  the  D —  in- 
dividuals, cannot  be  used  to  advantage  in  a  military  emer- 
gency which  demands  rapidity  of  training.  The  results 
of  army  mental  testing  indicate  that  the  majority  of  D  — 
and  E  soldiers  are  below  ten  years  mental  age.  A  few 
fall  as  low  as  three  or  four  years. 

The  contrast  between  A  and  D  —  intelligence  becomes 
impressive  when  it  is  shown  that  men  of  A  intelligence 
have  the  requisite  mental  ability  to  achieve  superior  rec- 
ords in  college  or  professional  school,  whereas  D —  in- 
dividuals are  rarely  able  to  pass  beyond  the  third  or 
fourth  grade  of  an  elementary  school,  however  long  they 
may  attend. 

Reliability  of  Methods. — The  methods  of  mental  exam- 
ining used  in  the  army  have  been  found  to  possess  relia- 
bility as  well  as  practical  value  which  far  exceeded  the 
expectations  of  the  men  who  are  responsible  for  them. 
Indeed,  the  success  of  this  particular  methodological 
undertaking  is  a  remarkable  demonstration  of  the  "fe- 
cundity of  aggregation.''  It  is  extremely  unlikely  that 
any  individual  working  alone  would  have  developed 
within  reasonable  time  equally  valuable  methods  of  group 
examining.    Inasmuch  as  reliability  is  of  first  importance, 


UTILIZATION  OF  BRAIN  POWER  IN  ARMY    199 

various  measures  of  the  validity  of  the  army  mental  tests 
are  presented. 

The  probable  error  of  an  Alpha  score  is  about  five 
points.  This  is  approximately  one-eighth  of  the  stand- 
ard deviation  of  the  scores  for  unselected  soldiers.  The 
reliability  coefficient  of  examination  Alpha  approximates 
.95.  This  group  examination  correlates  with  other  meas- 
ures of  mental  ability  as  follows:  (i)  With  officers'  rat- 
ings of  their  men,  .50  to  .70  for  the  total  Alpha  score 
and  .30  to  .54  for  the  separate  tests;  (2)  with  Stanford- 
Binet  measures  of  intelligence,  .80  to  .90  for  the  total 
Alpha  score  and  .31  to  .85  for  the  separate  tests ;  (3)  with 
the  Trabue  B  and  C  Completion  tests  combined,  ,J2  for 
the  total  score  and  .39  to  .76  for  the  separate  tests;  (4) 
with  Examination  Beta,  .80;  (5)  with  the  composite  re- 
sult of  Alpha,  Beta  and  Stanford-Binet  examinations, 
.94;  (6)  in  the  case  of  school  children  results  of  Alpha 
examination  correlate  (a)  with  teachers'  ratings  .67  to 
.82,  (^)  with  school  marks  .50  to  .60,  (c)  with  school 
grade  location  of  thirteen  and  fourteen-year-old  children 
.75  to  .91,  (fl?)  with  age  of  children  .83  (for  soldiers  the 
correlation  of  Alpha  score  with  age  is  practically  zero) . 

The  Alpha  examination  given  with  double  the  usual 
time  allowance  correlates  approximately  .97  with  the  reg- 
ular time  examination. 

The  following  data  indicate  the  reliability  of  Exami- 
nation Beta :  It  correlates  with  Alpha,  .80 ;  with  Stanford- 
Binet,  .73 ;  with  the  composite  of  Alpha,  Beta  and 
Stanford-Binet,  .915.  The  correlation  of  the  separate 
Beta  tests  with  the  Stanford-Binet  ranges  from  .47  to 
.63  (average  .58).  Results  of  Beta  given  with  double 
time  allowance  correlate  with  those  obtained  with  the 
regular  time  allowance  .95. 

For  the  several  forms  of  individual  examination  used 
in  the  army  the  principal  correlations  at  present  avail- 
able are  as  follows : 

Results  obtained  by  repetition  of  Stanford-Binet  ex- 


200  CONTEMPORARY  SCIENCE 

amination  of  school  children  correlate  .94  to  .97.  Results 
of  one-half  of  the  scale  compared  with  the  other  half 
correlate  .94  to  .96.  An  abbreviated  form  of  the  Stan- 
ford-Binet  examination  consisting  of  two  tests  per  year 
was  used  extensively  in  the  army.  The  results  of  this 
abbreviated  scale  correlate  .92  with  those  obtained  by 
use  of  the  complete  scale. 

For  the  Point  Scale  examination  the  measures  of  re- 
liability are  practically  the  same  as  for  the  Stanford- 
Binet. 

A  Performance  Scale  examination  prepared  especially 
for  military  use  consisted  of  ten  tests.  Results  for  the 
several  tests  of  the  scale  correlate  with  Stanford-Binet 
results,  .48  to  .78.  Five  of  the  ten  tests  yield  a  total  score 
which  correlates  .84  with  the  Stanford-Binet  score.  The 
same  five  tests  correlate  .97  with  the  results  of  the  entire 
scale. 

Summary  of  Results. — After  preliminary  trial  in  four 
contonmcnts  psychological  examining  was  extended  by 
the  War  Department  to  the  entire  army,  excepting  only 
field  and  general  officers.  To  supply  the  requisite  per- 
sonnel, a  school  for  training  in  military  psychology  was 
established  in  the  Medical  Officers'  Training  Camp,  Fort 
Oglethorpe,  Georgia.  Approximately  one  hundred  offi- 
cers and  more  than  three  hundred  enlisted  men  received 
training  at  this  school. 

The  work  of  mental  examining  was  organized  finally 
in  thirty-five  army  training  camps.  A  grand  total  of 
1,726,000  men  had  been  given  psychological  examination 
prior  to  January  i,  1919.  Of  this  number,  about  41,000 
were  commissioned  officers.  More  than  83,000  of  the  en- 
listed men  included  in  the  total  had  been  given  individual 
examination  in  addition  to  the  group  examination  for 
literates,  for  illiterates,  or  both. 

Between  April  27  and  November  30,  1918,  7,749  (0.5 
per  cent.)  men  were  reported  for  discharge  by  psychologi- 
cal examiners  because  of  mental  inferiority.    The  recom- 


UTILIZATION  OF  BRAIN  POWER  IN  ARMY   201 

mendations  for  assignment  to  labor  battalions  because  of 
low  grade  intelligence,  number  9,871  (0.6  +  per  cent.). 
For  assignment  to  development  battalions,  in  order  that 
they  might  be  more  carefully  observed  and  given  prelimi- 
nary training  to  discover,  if  possible,  ways  of  using  them 
in  the  army,  9,432  (0.6  -f-  P^^  cent.)  men  were  recom- 
mended. 

During  this  same  interval  there  were  reported  4,744 
men  with  mental  age  below  seven  years ;  7,762,  between 
seven  and  eight  years ;  14,566,  between  eight  and  nine 
years;  18,581,  between  nine  and  ten  years.  This  gives  a 
total  of  45,653  men  under  ten  years  mental  age.  It  is 
extremely  improbable  that  many  of  these  individuals  were 
worth  what  it  cost  the  government  to  maintain,  equip  and 
train  them  for  military  service. 

The  psychological  rating  of  a  man  was  reported 
promptly  to  the  personnel  adjutant  and  to  the  company 
commander.  In  addition,  all  low  grade  cases  and  men 
exhibiting  peculiarities  of  behavior  were  reported  also  to 
the  medical  officer.  The  mental  rating  was  thus  made 
available  for  use  in  connection  with  rejection  or  discharge, 
the  assignment  of  men  to  organizations  and  their  selection 
for  special  tasks.  The  mental  ratings  were  used  in  va- 
rious ways  by  commanding  officers  to  increase  the  effi- 
ciency of  training  and  to  strengthen  organizations  by  im- 
proved placement. 

It  was  recently  stated  and  emphasized  by  psychological 
examiners  that  a  man's  value  to  the  service  should  not  be 
judged  by  his  intelligence  alone,  but  that  instead  tem- 
peramental characteristics,  reliability,  ability  to  lead  and 
to  "carry  on"  under  varied  conditions  should  be  taken 
into  account.  Even  after  the  feasibility  of  securing  a 
fairly  reliable  measure  of  every  soldier's  intelligence  or 
mental  alertness  had  been  demonstrated,  it  remained  un- 
certain whether  these  measurements  would  correlate  posi- 
tively with  military  value  to  a  sufficient  degree  to  render 
them  useful.    Data  which  have  become  available  during 


202  CONTEMPORARY  SCIENCE 

the  past  year  settle  this  question  definitely  by  indicating 
a  relatively  high  correlation  between  officers'  judgments 
of  military  value  and  the  intelligence  rating. 

The  various  figures  herein  described  are  presented  not 
as  a  summary  of  the  results  of  psychological  examining  in 
the  army  but  instead  as  samples  of  these  results,  the 
chief  value  of  which  is  to  indicate  their  principal  relation- 
ship and  practical  values. 

Military  Applications  of  Mental  Ratings. — By  sample 
distribution  curves  Fig.  i  indicates  the  value  of  mental 
ratings  for  the  identification  and  segregation  of  different 
kinds  of  military  material.  The  illiterate  group  of  this 
figure  was  examined  by  means  of  Beta,  all  other  groups 
by  means  of  Alpha. 

Comparison  of  various  miHtary  groups  distinguished 
from  one  another  by  actual  attainment  in  the  service 
shows  that  the  psychological  tests  discriminate  between 
these  groups  with  definiteness.  This  point  may  be  illus- 
trated by  reference  to  the  percentages  of  men  of  different 
groups  making  A  and  B  grades  in  Examination  Alpha: 
officers,  83.0  per  cent. ;  officers'  training  school  candi- 
dates, 73.2  per  cent. ;  sergeants,  53.4  per  cent. ;  corporals, 
39.7  per  cent. ;  literate  privates,  18.8  per  cent.  The  com- 
parison of  measures  of  central  tendency  reveals  equally 
striking  differences.  Moreover,  within  the  officer  group 
itself  significant  differences  appear  for  different  branches 
of  the  service. 

The  relation  of  success  or  failure  in  officers'  training 
schools  to  intelligence  ratings  is  exhibited  by  Fig.  2,  in 
which  it  is  indicated  that  elimination  through  failure  in 
the  school  increases  rapidly  for  ratings  below  C  +.  Of 
men  rating  above  C  +»  8.65  per  cent,  were  eliminated;  of 
those  below  C  +,  52.27  per  cent.  The  data  for  this  figure 
were  obtained  from  three  schools  with  a  total  enrollment 
of  1,375  nien. 

Similarly  Fig.  3  indicates  the  relation  between  success  or 
failure  in  non-commissioned  officers'  training  schools  and 


UTILIZATION  OF  BRAIN  POWER  IN  ARMY   203 

intelligence  ratings.  The  elimination  increases  rapidly 
for  grades  below  C  +•  Of  men  rating  above  C,  only  18.49 
per  cent,  were  eliminated;  of  men  rating  below  C,  62.41 
per  cent.  The  results  presented  in  this  figure  were  0I3- 
tained  from  four  schools  with  a  total  enrollment  of  1,458 
men. 

Increasingly  extensive  and  effective  use  has  been  made 
of  the  psychological  rating  as  an  aid  in  the  selection  of 
men  for  officers'  training  schools,  non-commissioned  offi- 
cers' training  schools  and  other  lines  of  training  or  service 
which  require  special  ability.  It  has  been  convincingly 
demonstrated  that  the  data  of  psychological  examinations 
can  readily  be  used  to  diminish  the  necessary  elimination 
during  training  and  thus  to  increase  the  efficiency  of  the 
schools. 

The  extreme  differences  in  the  intellectual  status  of 
army  groups  are  fairly  indicated  by  Fig.  4,  which  pre- 
sents the  data  for  groups  whose  military  importance  can- 
not readily  be  overemphasized.  Roughly,  the  groups  in 
the  upper  half  of  the  figure  are  important  because  of 
their  relatively  high  intelligence  and  the  mental  initiative 
demanded  for  success,  whereas  those  in  the  lower  half 
of  the  figure  are  important  because  of  poor  intelligence 
and  relative  inefficiency  or  uselessness. 

These  results  suggest  that  if  military  efficiency  alone 
were  to  be  considered,  the  army  would  undoubtedly  gain 
largely  by  rejecting  all  D  —  and  E  men.  This  procedure 
would  greatly  lessen  the  group  of  disciplinary  cases  so 
troublesome  and  costly  in  the  military  organization  and 
also  the  group  which  in  the  figure  is  distributed  among 
"ten  poorest  privates,"  "men  of  low  military  value"  and 
"unteachable  men." 

Numerous  varieties  of  evidence  indicate  the  extreme 
military  importance  of  the  prompt  recognition  of  low 
grade  men.  The  percentages  of  men  ranking  below  the 
average  in  psychological  examinations  are  notably  large 
for  the  disciplinary  group,  men  having  difficulties  in  drill. 


204  CONTEMPORARY  SCIENCE 

men  reported  as  "unteachable"  and  men  designated  by 
their  officers  as  "poorest"  from  the  standpoint  of  military 
usefulness. 

The  comparison  of  negro  with  white  recruits  reveals 
markedly  lower  mental  ratings  for  the  former.  A  further 
significant  difference  based  on  geographic  classification  has 
been  noted  in  that  the  northern  negroes  are  mentally  much 
superior  to  the  southern. 

The  relation  between  officers'  judgments  of  the  value 
of  their  men  and  intelligence  ratings  is  exhibited  in  some- 
what different  ways  by  Figs.  5  to  7.  Thus  the  median 
scores  for  five  groups  of  privates  arranged  in  order  of 
military  value  from  "very  poor"  to  "best"  are  presented 
in  Fig.  5.  The  total  number  of  individuals  in  the  group 
is  374.  The  men  were  selected  from  twelve  different 
companies,  approximately  thirty  men  in  each  company 
being  ranked  by  an  officer  in  serial  order  from  "best"  to 
^'poorest."  The  rank  order  for  each  company  was  then 
correlated  by  the  psychological  examiner  with  the  rank 
order  supplied  by  psychological  examination.  In  seven  of 
the  twelve  companies  the  correlations  ranged  from  .64  to 
,75.  The  average  correlation  was  .536.  These  correla- 
tions are  high,  considering  the  large  number  of  factors 
which  may  influence  a  man's  value  to  the  service. 

The  median  score  for  the  "very  poor"  group  of  Fig.  5 
is  28  points  in  an  examination  whose  maximal  score  is 
212  points.  By  contrast  with  this,  the  median  score  of 
the  "best"  group  of  privates  is  99  points. 

The  commanding  officers  of  ten  different  organizations, 
representing  various  arms  of  the  service,  in  a  certain  camp 
were  asked  to  designate  ( i )  the  most  efficient  men  in  their 
organizations,  (2)  the  men  of  average  ability  and  (3) 
men  so  inferior  that  they  are  "barely  able"  to  perform 
their  duties. 

The  officers  of  these  organizations  had  been  with  their 
men  from  six  to  twelve  months  and  knew  them  exception- 
ally well.    The  total  number  of  men  rated  was  965,  about 


UTILIZATION  OF  BRAIN  POWER  IN  ARMY   205 

equally  divided  among"  "best,"  "average,"  and  "poorest." 
After  the  officers'  ratings  had  been  made,  the  men  were 
given  the  usual  psychological  test.  Comparison  of  test 
results  with  officers'  ratings  showed : 

(a)  That  the  average  score  of  the  "best"  group  was 
approximately  twice  as  high  as  the  average  score  of 
the  "poorest"  group. 

(b)  That  of  men  testing  below  C — ,  70  per  cent,  were 
classed  as  "poorest"  and  only  4.4  per  cent,  as  "best." 

(c)  That  of  men  testing  above  C  -|->  ^5  P^^"  cent,  were 
classed  as  "poorest"  and  55.5  per  cent,  as  "best." 

(d)  That  the  man  who  tests  above  C  +  is  about  four- 
teen times  as  likely  to  be  classed  "best"  as  the  man 
who  tests  below  C  — . 

(e)  That  the  per  cent,  classed  as  "best"  in  the  various 
groups  increased  steadily  from  o  per  cent,  in  D  —  to 
57.7  per  cent,  in  A,  while  the  per  cent,  classed  as 
"poorest"  decreased  steadily  from  80  per  cent,  in 
D —  to  1 1.5  per  cent,  in  A. 

In  an  infantry  regiment  of  another  camp  were  765 
men  (regulars)  who  had  been  with  their  officers  for  sev- 
eral months.  The  company  commanders  were  asked  to 
rate  these  men  as  i,  2,  3,  4  or  5  according  to  "practical 
soldier  value,"  i  being  highest  and  5  lowest.  The  men 
were  then  tested,  with  the  following  results : 

(a)  Of  76  men  who  earned  the  grade  A  or  B,  none 

was  rated  "5"  and  only  9  were  rated  "3"  or  "4." 
(&)  Of  238  "D"  and  "D— "  men,  only  one  received 
the  rating  "i,"  and  only  7  received  a  rating  of  "2." 
(c)  Psychological  ratings  and  ratings  of  company  com- 
manders were  identical  in  49.5  per  cent,  of  all  cases. 
There  was  agreement  within  one  step  in  88.4  per  cent, 
of  ca'ses,  and  disagreement  of  more  than  two  steps 
in  only  .7  per  cent,  of  cases. 
Fig.  6  exhibits  a  striking  contrast  in  the  intelligence 
status  and  distribution  of  "best"  and  "poorest"  privates. 
The  personal  judgment  data  for  this  figure  were  obtained 


2o6  CONTEMPORARY  SCIENCE 

from  sixty  company  commanders  who  were  requested  to 
designate  their  ten  "best"  and  their  ten  "poorest"  privates. 
Of  the  "poorest,"  57.5  per  cent,  graded  D  or  D  — ;  less 
than  3  per  cent,  graded  A  or  B.  The  results  suggest  that 
intelligence  is  likely  to  prove  the  most  important  single 
factor  in  determining  a  man's  value  to  the  military  ser- 
vice. 

In  one  training  camp  excellent  opportunity  was  of- 
fered to  compare  a  group  of  soldiers  selected  on  the  basis 
of  low  military  value  with  a  complete  draft  quota.  In 
the  "low  value"  group  there  were  147  men,  in  the  com- 
plete draft  quota  12,341  men.  The  distributions  of  intel- 
ligence ratings  for  these  two  military  groups  appear  as 
Fig.  7,  from  which  it  is  clear  that  if  all  men  with  intelli- 
gence ratings  below  C —  had  been  eliminated,  the  "low 
value"  group  would  have  been  reduced  by  at  least  half. 

In  a  certain  training  camp  221  inapt  soldiers,  belong- 
ing to  a  negro  regiment  of  Pioneer  Infantry,  were  re- 
ferred by  their  commanding  officer  for  special  psychologi- 
cal examination.  Nearly  one-half  (109)  of  these  men 
were  found  to  have  mental  ages  of  seven  years  or  less. 
The  army  nevertheless  had  been  attempting  to  train  these 
men  for  military  service.  In  justice  to  the  Psychological 
Service  it  should  be  stated  that  these  negroes  had  been 
transferred  from  camps  where  there  were  no  psychologi- 
cal examiners.  For  this  reason  they  had  not  been  ex- 
amined before  being  assigned  to  an  organization  for 
regular  training. 

In  another  instance  some  306  soldiers  from  organiza- 
tions about  to  be  sent  overseas  were  designated  by  their 
commanding  officers  as  unfit  for  foreign  service.  They 
were  referred  for  psychological  examination  with  the  re- 
sult that  90  per  cent,  were  discovered  to  be  ten  years  or 
less  in  mental  age,  and  80  per  cent,  nine  years  or  less. 

It  has  been  discovered  that  when  soldiers  are  assigned 
to  training  units  without  regard  to  intelligence,  extreme 
inequalities  in  the  mental  strength  of  companies  and  regi- 


UTILIZATION  OF  BRAIN  POWER  IN  ARMY   207 

ments  appear.  This  fact  is  strikingly  exhibited  by  Figs. 
8  and  9,  of  which  the  former  shows  the  proportions  of 
high  grade  and  of  illiterate  or  foreign  soldiers  in  the 
various  companies  of  an  infantry  regiment.  Compare,  for 
example,  the  intelligence  status  of  C  and  E  companies. 
The  former  happens  to  have  received  only  3  per  cent,  of 
A  and  B  men  along  with  38  per  cent,  of  ilHterates  and 
foreigners,  the  latter  received  by  contrast  29  per  cent,  of 
high  grade  men  with  only  9  per  cent,  of  men  who  are  as  a 
rule  difficult  to  train.  It  is  needless  to  attempt  to  empha- 
size the  military  importance  of  this  condition.  The  tasks 
of  the  officers  of  these  two  companies  are  wholly  incom- 
parable, but  more  serious  even  than  the  inequalities  in 
response  to  training  are  the  risks  of  weak  points  in  the 
army  chain  as  a  result  of  such  random  or  unintelligent 
assignment. 

Naturally  enough  the  officers  of  the  army  were  quick 
to  appreciate  the  disadvantages  of  a  method  of  assigning 
recruits  which  permits  such  extreme  inequalities  in  men- 
tal strength  to  appear  and  persist.  They  promptly  de- 
manded the  reorganization  of  improperly  constituted  units 
and  assignment  in  accordance  with  intelligence  specifica- 
tions so  that  the  danger  of  weak  links  in  the  chain  and  of 
extreme  difference  in  rapidity  of  training  should  be  mini- 
mized. 

That  serious  inequalities  existed  in  regiments  as  well 
as  in  smaller  units  prior  to  assignment  on  the  basis  of  in- 
telligence is  proved  by  the  data  of  Fig.  9,  which  records 
the  differences  found  in  four  infantry  regiments  and  three 
regiments  of  field  artillery. 

Following  the  demonstration  of  the  value  of  psychologi- 
cal ratings  in  connection  with  assignment,  the  experiment 
was  tried  in  various  camps  of  classifying  men  in  accord- 
ance with  intelligence  for  facilitation  of  training.  To  this 
end  A  and  B  grade  men  were  placed  in  one  training  group, 
C  +»  C  and  C  —  men  in  another,  and  D  and  D  —  men  in 
a  third.    The  three  groups  were  then  instructed  and  drilled 


2o8  CONTEMPORARY  SCIENCE 

in  accordance  with  their  ability  to  learn.  Thus  delay  in 
the  progress  of  high  grade  men  was  avoided  and  the  low 
grade  soldiers  were  given  special  instruction  in  accord- 
ance with  their  needs  and  capacity. 

The  marked  differences  in  the  mental  strength  of  groups 
in  different  officers'  training  schools  are  shown  by  Fig. 
ID.  For  the  eighteen  schools  of  this  figure,  the  propor- 
tion of  A  grades  varies  from  16.6  per  cent,  to  62.4;  the 
proportion  of  A  and  B  grades  combined,  from  48.9  per 
cent,  to  93.6  per  cent. ;  and  the  proportion  of  grades  below 
C  +,  from  o  to  17.9  per  cent.  Since  it  is  unusual  for  a 
man  with  an  intelligence  rating  below  C  +  to  make  a  sat- 
isfactory record  in  an  officers'  training  school,  it  is  clear 
that  the  pedagogic  treatment  of  these  several  student 
groups  should  differ  more  or  less  radically  and  that  elimi- 
nation must  vary  through  a  wide  range  if  the  several 
schools  are  to  graduate  equally  satisfactory  groups  of 
officers. 

Far  more  important  than  the  contrast  in  student  officers 
training  groups  noted  above  are  the  differences  in  the  in- 
telligence status  of  officers  in  different  arms  of  the  service 
as  revealed  by  psychological  examining.  Figure  11  ex- 
hibits the  data  obtained  for  several  groups.  The  varia- 
tions are  extreme  and  seemingly  unrelated  to  the 
requirements  of  the  service.  Medical  officers,  for  ex- 
ample, show  a  relatively  large  percentage  of  men  rating 
C  -j-  or  below,  whereas  engineering  officers  head  the  list 
with  relatively  few  men  whose  intelligence  is  rated  below 
B.  There  is  no  obvious  reason  for  assuming  that  the 
military  duties  of  the  engineer  demand  higher  intelligence 
or  more  mental  alertness  than  do  those  of  the  medical 
officer.  Since  it  is  improbable  that  any  arm  of  the  ser- 
vice possesses  more  intelligence  than  can  be  used  to  ad- 
vantage, the  necessary  inference  is  that  certain  arms 
would  benefit  by  the  elimination  of  low  grade  men  and  the 
substitution  of  officers  with  better  intellectual  ability. 

Relation  of  Intelligence  to  Occupation. — The  occupa- 


UTILIZATION  OF  BRAIN  POWER  IN  ARMY   209 

tional  classification  of  soldiers  in  the  army  afforded  op- 
portunity for  a  study  of  the  relation  of  intelligence  to 
occupation.  Various  features  of  this  relation  are  exhibited 
for  a  few  military  occupations  by  Fig.  12,  in  which  are 
represented  the  proportions  of  the  several  grades  of  in- 
telligence for  the  several  occupations. 

In  order  of  diminishing  intelligence  exhibited  these 
groups  may  be  classified  as  follows:  professions,  clerical 
occupations,  trades,  partially  skilled  labor  and  unskilled 
labor.  The  greatest  differences  in  intelligence  required  or 
exhibited  appear  at  the  upper  end  of  the  scale,  whereas 
the  differences  within  the  trade  group  are  relatively  small. 
The  differences  in  range  of  intelligence  occurring  in  the 
several  occupations  are  considerable  and  in  all  probability 
significant.  In  general  the  range  diminishes  from  un- 
skilled labor  to  intellectually  difficult  professions. 

The  data  of  this  occupational  study,  which  are  merely 
sampled  by  Fig.  12,  suggest  both  the  possibility  and  de- 
sirability of  preparing  intelligence  specifications  for  use 
in  connection  with  civilian  occupations.  Such  specifica- 
tions, if  satisfactorily  prepared,  should  be  useful  alike  as 
partial  basis  for  educational  advice  and  procedure  and 
subsequently  for  vocational  guidance.  It  must  be  em- 
phasized in  this  connection  that  the  data  of  Fig.  12  are 
not  strictly  comparable  with  such  information  as  may  be 
gathered  concerning  civilian  groups  because  various  se- 
lectional  factors  operate  in  the  army. 

The  Applicability  of  Mental  Measurements. — The  utili- 
zation of  methods  of  mental  testing  by  the  army  has  at 
once  increased  military  efficiency  by  the  improved  utili- 
zation of  brain  power  and  demonstrated  the  applicability 
of  the  group  method  of  measuring  intelligence  to  educa- 
tional and  industrial  needs.  The  army  methods,  although 
not  adapted  to  the  usual  educational  or  industrial  re- 
quirements, can  readily  be  modified  or  used  as  a  basis  for 
die  development  of  similar  procedures. 

There  are  abundant  indications  that  the  future  will  wit- 


2IO  CONTEMPORARY  SCIENCE 

ness  the  rapid  development  of  varied  methods  for  improv- 
ing scientific  placement  and  vocational  guidance.  It  is 
highly  probable  that  grading  in  the  public  schools,  in  col- 
leges and  professional  schools  will  shortly  be  based  in  part 
upon  measurement  of  mental  ability  instead  of  exclusively 
on  measurements  of  acquisition.  The  war  has  worked  a 
miracle  for  what  may  properly  be  called  mental  engineer- 
ing by  precipitating  expectations,  surmises  and  desires 
w^hich  have  long  sought  expression.  Yesterday  a  few 
men  believed  in  the  probability  of  the  early  appearance 
and  practical  usefulness  of  this  new  branch  of  engineer- 
ing; to-day  scores  of  business  men,  educators  and  men  of 
other  scientific  professions  are  convinced  that  it  has  ar- 
rived and  demand  its  rapid  and  effective  development. 

The  complete  scientific  report  on  the  psychological 
data  which  the  army  has  supplied  and  of  which  mere 
glimpses  have  been  given  in  this  article  should  constitute 
the  basis  for  further  important  advances  in  methods  of 
mental  measurement  and  should  greatly  add  to  the  knowl- 
edge of  the  distribution  of  intelligence  and  its  varied  and 
significant  relations.  These  reports  are  in  preparation 
and  it  is  hoped  that  they  may  be  published  without  undue 
delay. 


XII.    CONCEPTIONS    AND    MISCONCEPTIONS 
IN   PSYCHOANALYSIS 

(Read  before  the  Harvey  Society  of  Johns  Hop- 
kins University) 

BY 

Trigant  Burrow,  M.D. 

Not  infrequently  a  discussion  purporting  to  relate  to  a 
given  subject  expresses  nothing  more  than  the  unsophis- 
ticated views  of  the  speaker  concerning  some  notion  or 
other  which  he  mistakenly  conceives  the  subject  to  be. 
Perhaps  no  theme  has  suffered  more  from  the  disfigure- 
ments of  these  naive  tendencies  than  psychoanalysis,  so 
that  one  does  well  to  distinguish  between  psychoanalysis 
and  rumors  of  psychoanalysis. 

The  truth  is,  psychoanalysis  labors  under  the  grave  dif- 
ficulties surrounding  any  subject  which  offers  us  an  en- 
tirely novel  point  of  interpretation;  and  far  more 
formidable  than  the  barriers  of  novelty  and  strangeness  is 
the  fact  that  psychoanalysis  is  a  method  which  is  essentially 
revolting  to  our  conventional  social  consciousness,  entail- 
ing harsh  incriminations  from  which  we  would  prefer  to 
turn  away.  It  is  a  therapeutic  procedure  which  our  moral 
conventions  hold  in  natural  repugnance;  it  is  an  unpleas- 
ant discipline  that  thrusts  before  us  those  things  which  we 
dislike  to  look  on.  But  if  the  theory  on  which  the  method 
rests  is  correct,  such  an  inbred  antagonism  to  the  precepts 
of  psychoanalysis  is  of  the  very  essence  of  its  thesis,  for 

211 


212  CONTEMPORARY  SCIENCE 

psychoanalysis,  rightly  understood,  is  a  method  of  treat- . 
ment  based  on  the  recognition  of  a  psychic  conflict  in  the 
life  of  the  patient  arising  precisely  from  his  inherent  re- 
vulsion against  the  artificial  inhibitions  which  are  imposed 
on  him  under  the  constitution  of  society.  The  conflict  is 
therefore  a  social  one. 

It  would  seem,  then,  that  we  all  have  within  us  the 
elements  of  the  neurotic  diathesis;  that  the  difference 
between  the  normal  and  the  neurotic  is  more  a  matter 
of  circumstances  than  of  constitution;  that  the  interval 
between  the  two  is  proportional  rather  than  generic. 

If,  therefore,  psychoanalysis,  unlike  the  gently  concilia- 
tory procedures  characteristic  of  other  forms  of  psycho- 
therapy, is  a  method  whose  specific  task  it  is  to  lay  bare 
the  pious  devices  through  which  we  seek  to  evade  life's 
sterner  verities,  we  shall  very  naturally  incline  to  resent 
it  as  an  impertinent  intrusion.  Indeed,  it  requires  no  small 
measure  of  courage  to  view  with  equanimity  the  unwel- 
come factors  which  psychoanalysis  thrusts  before  our 
eyes. 

It  is,  then,  because  of  the  essential  significance  of 
psychoanalysis,  with  its  open  hostility  to  the  wide  social 
repression  of  those  insatiate  biologic  demands  which  be- 
long, broadly  speaking,  to  the  sexual  sphere,  and  the 
consequent  affront  it  offers  to  our  habitual  sense  of  out- 
ward reserve,  that  I  am  led  to  utter  a  warning  lest  in 
estimating  the  value  of  this  inimical  method  we  allow 
traditional  prejudice  to  distort  our  judgment. 

The  psychoanalytic  method,  introduced  by  Sigmund 
Freud,  is,  of  course,  concerned  solely  with  the  treatment 
of  nervous  disorders.  In  reality  the  term  "nervousness" 
or  "neurosis,"  as  commonly  applied,  is  etymologically  mis- 
leading, for  the  morbid  condition  involved  in  such  psychic 
disturbances  is  not  neural ;  it  is  moral.  There  is  question 
not  of  a  disease  of  the  tissues  but  of  a  disharmony  of  the 
personality ;  not  of  a  lesion  of  organs  but  of  a  schism  of 
consciousness.    We  are  dealing  not  with  the  pathology  of 


CONCEPTIONS  AND  MISCONCEPTIONS    213 

the  neural  elements  but  with  the  psychology  of  the  social 
element  as  presented  in  the  individual  unit,  for  the  dis- 
turbances with  which  psychoanalysis  has  to  cope  entail  in 
every  instance  a  psychic  disharmony  based  on  the  indi- 
vidual's relation  to  the  social  environment.  It  is  an  in- 
teresting fact  that  in  every  psychoanalysis  there  is  dis- 
covered the  influence  of  some  hidden  presence  who  stands 
in  such  instance  in  the  closest  personal  relation  to  the 
patient  and  constitutes  the  important  factor  in  the  produc- 
tion of  the  neurosis. 

Before  considering,  however,  the  theory,  the  instruments 
and  the  aims  of  psychoanalysis,  it  may  be  well  to  mention 
certain  misconceptions  in  regard  to  the  method.  Perhaps 
we  shall  gain  ground  if,  before  attempting  to  say  some- 
thing of  what  psychoanalysis  is,  1  say  a  word  as  to  what 
psychoanalysis  is  not. 

Already  I  have  made  intimation  of  the  element  of  sex- 
uality as  an  etiologic  factor  in  the  manifestations  we  call 
neurotic.  Many  will  doubtless  have  heard  of  the  inevitable 
implication  in  the  psychoanalytic  method  of  treatment  of 
the  sexual  sphere  of  the  patient's  life.  Some  probably 
will  either  have  explicitly  heard,  or  have  tacitly  gathered, 
that  psychoanalytic  presupposes  the  existence  in  the  life 
of  the  patient  of  some  secret  perversion  of  the  sexual  in- 
stinct, and  that  it  is  the  task  of  the  psychoanalyst  to  extort 
a  confession  of  some  such  hidden  misdemeanor.  There- 
fore it  is  but  natural  if,  from  the  prevailing  trend  of  cur- 
rent hearsay,  it  will  have  been  inferred  that  this  new 
method  of  psychotherapy  proceeds  on  the  assumption  that 
nervous  disorders — hysteria,  obsessional  and  imperative 
states,  so-called  neurasthenia  and  psychasthenia — are  in- 
variably to  be  explained  by  the  hidden  presence  of  some 
abnormal  mode  of  sexual  indulgence,  and,  therefore,  the 
origin  of  a  neurosis,  according  to  Freud's  interpretation, 
is  linked  with  the  idea  of  some  species  of  sexual  delin- 
quency. 

As  widespread  as  this  conception  has  become,  nothing 


214  CONTEMPORARY  SCIENCE 

could  be  further  from  the  truth.  In  point  of  fact,  the 
proposition  it  maintains  is  precisely  the  contrary  of  that 
posited  by  psychoanalysis.  In  his  "Drei-Abhandlungen 
zur  Sexualtheorie,"  Freud  ^  clearly  defines  the  neurosis 
as  the  negation  of  abnormal  sexuality.  He  distinctly  says 
that  the  neurotic  and  the  sexual  delinquent  stand  at  exactly 
opposite  poles  to  one  another.  It  cannot  be  too  strongly 
emphasized,  therefore  that  the  manner  in  which  the  pa- 
tient's sexuality  is  related,  according  to  Freud's  interpre- 
tation, to  the  etiology  of  neurotic  disorders  is  one  which, 
far  from  incriminating  him,  wholly  absolves  him  from 
the  stigma  of  abnormal  sexuality. 

Still  another  very  prevalent  misapprehension  is  the 
view  that  psychoanalysis  is  synonymous  with  the  obtaining 
of  a  general  confession  from  the  patient. 

Far  be  it  from  me  to  deny  the  time-honored  psycho- 
therapeutic axiom  that  an  honest  confession  is  good  for 
the  soul.  No  one,  I  think,  realizes  better  than  the  psycho- 
pathologist  the  undoubtedly  remedial  effect  which  follows 
on  the  unbosoming  of  some  secret  conflict  in  the  mental 
life.  But  the  whole  point  in  the  psychoanalytic  interpreta- 
tion of  the  neuroses  is  that  these  disorders  arise  precisely 
from  conditions  which  render  voluntary  confession  im- 
possible, it  being  the  nature  of  the  disturbing  element  that 
it  remains  of  necessity  wholly  unknown  to  the  patient 
himself. 

The  typical  clinical  picture  confronting  the  psychoana- 
lyst is  that  of  an  individual  who,  on  examination,  either  re- 
veals no  evidence  of  disease  whatever,  or  else  presents  a 
condition  which  cannot  be  accounted  for  by  any  demon- 
strable physical  lesion.  Indeed,  it  is  not  infrequent  that 
in  the  opinion  of  the  ablest  clinical  experts  he  is  pro- 
nounced absolutely  free  from  organic  disorder.  Often  the 
patient  himself  declares  that  he  feels  in  excellent  physical 
condition,  that  he  eats  wholesomely,  sleeps  soundly,  and 

^  Freud,  Sigmund :  Drei  Ahhandlung en  sur  Sexualtheorie, 
Vienna,  Deuticke,  1910. 


CONCEPTIONS  AND  MISCONCEPTIONS    215 

realizes  that  he  has  everything  that  ought  to  make  a  man 
well  and  happy,  and  yet  whose  every  moment  is  one  of 
unmitigated  wretchedness.  He  is  perhaps  a  prey  to  pho- 
bias, obsessions,  apprehensions,  depressions,  sudden  and 
unremitting  imperatives,  the  appalling  loss  of  the  sense 
of  reality,  to  mention  the  most  characteristic  symptoms 
of  neurotic  states,  or  he  may  suffer  from  digestional  dis- 
turbance, respiratory  inhibition  (stammering),  muscular 
contractions,  etc.,  and  yet  is  utterly  perplexed  to  account 
for  the  plight  in  which  he  finds  himself,  and  completely 
powerless  to  furnish  data  that  might  throw  light  on  these 
abnormal  manifestations. 

In  other  words,  we  are  in  the  presence  of  factors  which 
operate  unconsciously.  That  is,  we  have  to  do  with  or- 
ganic effects  and  reactions  which  fail  to  attain  the  level 
of  conscious  perception  and  which  are  therefore  from 
the  conscious  standpoint  equally  impalpable  to  patient  and 
physician.  Let  us  bear  in  mind,  then,  that  the  sphere  of 
psychoanalysis  lies  exclusively  in  the  field  of  unconscious 
mentation. 

With  these  distinctions  before  us,  I  shall  try  to  explain 
briefly  the  basic  principles  of  psychoanalysis,  and  to  show 
something  of  what  the  method  seeks  to  attain. 

In  many  fundamental  respects,  Freud's  teaching,  as  has 
been  said,  marks  a  wide  departure  from  the  hitherto  pre- 
vailing view  as  to  the  interpretation  of  neurotic  states.^ 

In  the  first  place,  Freud  ascribes  all  neurotic  disorders 
to  the  existence  in  the  patient  of  wishes  which  are  un- 
recognized, that  is,  not  directly  envisaged  by  him.  Wishes 
of  this  unpremeditated  character  he  subsumes  under  the 
term  "unconscious,"  and  gives  to  the  realm  of  psychic 
activity  constituting,  as  it  were,  the  abode  of  such  uncon- 
scious trends,  the  name  of  "the  unconscious'*  (das  Un- 
hewusstsein) . 

Secondly,  he  regards  the  neurosis  as  a  spontaneous  ex- 

2 Forchheimer,  Frederick:  Therapeusis  of  Internal  Diseases, 
New  York,  D.  Appleton  &  Co.,  1913,  4,  569. 


2i6  CONTEMPORARY  SCIENCE 

pression  of  the  tendency  toward  the  fulfilment  of  sucK 
unconscious  wishes.  Thus  he  ascribes  to  the  neurosis  a 
purposive  significance — a  moral  import.  The  neurosis 
contains  a  motive.  It  embodies  an  underlying  intention: 
tends  to  supply  a  void  not  clearly  cognized  and  defined, 
because  existing  outside  the  precincts  of  consciousness. 

Thirdly,  the  ideas  or  wishes  which  thus  occupy  the 
sphere  of  unconsciousness  possess  the  generic  character 
of  being  invariably  such  as  are  ethically  inadmissible  in 
the  sight  of  consciousness,  so  that  the  psychologic  account 
of  the  creation  of  this  limbo  of  the  unconscious  is  to  be 
found  in  the  psychic  conflict  arising  out  of  the  opposition 
of  consciousness  to  these  ethically  unwelcome  desires  and 
their  consequent  enforced  banishment  from  consciousness 
— a  process  which  Freud  calls  the  mechanism  of  repres- 
sion (Verdrdngung).^  Hence,  in  accordance  with  the 
hypothesis,  a  psychic  conflict,  with  the  attendant  re- 
pression of  the  unseemly  element,  is  the  basic  factor  in 
the  production  of  the  neuroses. 

Fourthly,  it  is  Freud's  thesis  that  all  such  conflicts  as 
issue  in  such  unconscious  repression  have  their  ultimate 
basis  in  the  sphere  of  the  sexual  instinct.  In  other  words, 
psychoanalysis  posits  a  sexual  repression  as  the  essential 
condition  in  the  etiology  of  a  neurosis.^ 

And  lastly,  the  theory  assumes  that  such  symptoms  as 
are  the  expression  of  a  tendency  toward  the  fulfilment  of 
these  forbidden  trends  are  but  an  indirect,  cunningly 
veiled  representation  of  them ;  that  they  are  substitutions 
employed  by  reason  of  their  associative  affiliation  with  the 
original  underlying  idea.     Each  symptom  is  the  dramatic 

3  Brewer  and  Freud :  Studien  iiber  Hysterie,  Vienna,  Deuticke, 
1910. 

*  It  should  be  explained,  however,  that  the  word  "sexual,"  as 
Freud  uses  it,  has  a  far  more  general  and  inclusive  meaning  than 
is  conveyed  by  the  term  as  commonly  employed.  Contrary  to 
the  specific  connotation  of  conventional  usage,  the  term  denotes, 
with  Freud,  the  entire  sphere  of  the  primary,  biologic  pleasure- 
affects. 


CONCEPTIONS  AND  MISCONCEPTIONS    217 

portrayal  of  the  repressed  wish  subjected  to  a  process  of 
modification  through  the  effort  of  consciousness  to  evade 
its  real  significance.  The  symptoms  thus  expressive  of 
a  neurosis  are  in  each  instance  the  resultant  of  contrary 
and  opposed  psychic  trends,  and  represent  in  their  outcome 
a  compromise  between  the  two. 

Such  remodeled,  distorted  expressions  of  the  brute, 
primitive  instincts  as  appear  in  the  symptoms  of  neurotic 
disorders,  Freud  has  called  the  phenomena  of  unconscious 
symbolization.  This  unconscious  symbolization  of  instinc- 
tive trends  whereby  is  effected  the  necessary  palliation 
required  by  the  censor  of  consciousness  is  the  crux  of 
Freud's  interpretation  of  the  neuroses. 

According  to  Freud,  the  instinct  of  reproduction  is 
paramount  in  the  life  of  the  individual.  Yet  the  sexual 
trend  is  not  the  simple,  unitary,  static  phenomenon  it  is 
generally  assumed  to  be,  but,  like  other  factors  of  evolu- 
tion, IS  a  dynamic  process  having  its  integrative  compon- 
ents derived  from  simpler  elements.  Freud  points  out 
that  the  sensations  contributory  to  this  impulse  are  origi- 
nally composed  of  dispersed  and  inarticulate  components, 
having  their  seats  in  various  erogenic  zones  located  over 
the  body  surface  and  situated  chiefly  in  the  regions  com- 
posing the  body  orifices.  The  sensations  arising  from  such 
erogenic  zones  are  present,  he  tells  us,  in  earliest  infancy, 
and  it  is  of  these  scattered,  incoherent  elements  that  the 
characteristic  sexual  feelings  pertaining  specifically  to  the 
organs  of  reproduction  are  later  constituted.  The  ulti- 
mate attainment  of  the  instinct  directly  conducive  to  re- 
production consists,  then,  of  a  process  of  integration  rep- 
resenting the  product  of  individual  evolution.  Accord- 
ingly, there  are  three  possible  courses  in  the  development 
of  the  ultimate  sexual  life  of  the  individual: 

First,  the  sexual  life  may  take  a  normal  course  leading 
to  the  gradual  absorption,  so  to  speak,  of  these  scattered 
auto-erotic  trends  into  the  resultant  allo-erotic  instinct 
comprised  in  the  ultimate  reproductive  quest,  and  having 


2i8  CONTEMPORARY  SCIENCE 

Its  physiologic  center  in  the  organs  of  generation.  In 
such  case  we  have  the  integration  which  results  in  the 
individual  of  a  normal  sexual  life. 

Secondly,  there  may  be  a  persistence  of  the  original 
auto-erotic  interests  and  of  the  sexual  satisfaction  attach- 
ing to  these  primary  erogenic  zones,  with  failure  of  the 
aforesaid  integration  into  the  sexual  impulse  which  tends 
toward  the  goal  of  reproduction.  In  this  case  there  are 
presented  the  variations  of  the  normal  sexual  impulse 
which  constitute  the  perversions. 

Finally,  the  sexual  interest  or  libido  pertaining  to  the 
different  erogenic  zones  through  repression  may  be  de- 
flected into  vicarious  avenues  of  sexuality  corresponding 
symboHcally  to  such  frustrated  interests.  Such  an  out- 
come epitomizes  the  mechanism  of  the  neuroses  as  en- 
visaged by  Freud.  Of  course  no  rigid  line  of  demarca- 
tion separates  these  three  possible  developmental  issues, 
but  there  is  among  them  more  or  less  of  interlacement  of 
the  characters  distinctive  of  each. 

The  neuroses,  then,  represent  in  a  negative  way  a  mis- 
carriage of  the  sexual  instinct  analogous  to  that  repre- 
sented in  a  positive  way  in  the  sexual  perversions. 
Freud's  thesis,  therefore,  is  that  the  neuroses  betray  an 
inadequacy  in  the  development  of  the  psycho-sexual  life. 
This  inadequacy  marks  a  regression  toward  a  sexual 
mode  appropriate  to  an  earlier,  infantile  period  and  pos- 
tulates a  latent,  unconscious  fixation  of  the  libido  on  its 
original,  infantile  object.  Hence  the  sexuality  of  the 
neurotic  is  hindered,  repressed  and,  as  it  were,  preoccu- 
pied elsewhere  than  with  the  immediate  and  contemporary 
object  of  sexual  interest,  and  the  psychologic  situation 
presented  by  the  patient  is  summed  up  by  Freud  in  what 
he  terms  the  patient's  "sexual  resistances"  (die  sexuelle 
Widersfdnde) . 

Such  is  the  fundamental  idea  of  psychoanalysis  in  re- 
gard to  the  origin  and  development  of  the  neuroses.  The 
primary  factor  in  the  production  of  the  disorders  is  the 


CONCEPTIONS  AND  MISCONCEPTIONS    219 

repression  of  the  individuars  sexuality  due  to  the  ban  set 
on  the  manifestations  of  this  elemental  instinct  by  the 
strictures  of  social  and  religious  conventions.  It  is  the 
conflict  between  the  forces  of  artificial  culture  and  those 
of  an  inherent  instinct  of  sex,  the  former  imposing  the 
repudiation  of  sexuality,  the  latter  insisting  as  resolutely 
on  a  due  recognition  of  the  basal  significance  of  this  ele- 
mental factor  in  the  biologic  economy.  The  sexual  instinct 
stoutly  insists  that  it  be  granted  recognition  in  conscious- 
ness, and  consciousness,  in  its  narrow  intolerance,  is  as 
fiercely  resolved  to  debar  so  unseemly  an  intruder.  The 
final  upshot  of  the  situation  is  a  compromise.  It  is  agreed 
that  the  unruly  element  be  admitted  to  consciousness  on 
condition  that  it  soften  its  tone  and,  as  it  were,  adopt  con- 
ventional apparel  conformable  to  the  requirements  of 
adult,  social  consciousness.  It  is  to  this  end  that  the 
psychic  organism  assumes  the  social  defense  it  finds  in 
the  elaborate  metaphorical  usages  presented  in  the  pa- 
tient's "symptoms."  For  it  is  only  through  dissembling 
that  the  repressed  complex  can  succeed  in  evading  the 
anathema  of  the  conscious  censor.  But,  though  disguised 
in  consciousness,  this  discordant,  outlawed  element  still 
lurks  in  the  unconscious,  where,  acting  surreptitiously,  it 
incites  dissension  amid  the  constituents  of  the  personality, 
impairing  its  unity  and  destroying  the  mental  synthesis 
requisite  to  the  purposes  of  concerted  function. 

It  is  Freud's  thesis,  then,  that  the  neurosis  entails  a 
psychic  conflict  due  to  an  attempt  to  exclude  from  a  fit 
acknowledgment,  in  consciousness,  the  biologic  factors 
whose  prerogatives  are  fundamental  and  inalienable.  As 
has  been  said,  such  an  exclusion  of  normal  interests  from 
participation  in  current  consciousness  Freud  calls  a  re- 
pression. A  psychic  repression  being  the  essential  mech- 
anism of  a  neurosis,  the  question  for  psychotherapeutics 
is,  How  may  disorders  arising  from  a  psychic  conflict, 
issuing  out  of  the  arbitrary  and  extraneous  repression 
from  consciousness  of  such  contraband  associations,  be 


220  CONTEMPORARY  SCIENCE 

remedied?  Freud,  seeking  to  give  the  direct  logical  an- 
swer, contends  that  disorders  embodying  psychic  conflicts 
due  to  repression  of  elements  which  have  a  right  to  ten- 
ancy in  consciousness  are  to  be  effectually  cured  only  by 
removing  the  repression  and  freely  admitting  such  con- 
tingents to  their  hereditary  rights  in  consciousness. 

So  much  by  way  of  outline  of  the  principles  contained 
in  Freud's  system  of  psychotherapy.  Now  as  to  the 
method. 

J 

METHOD    OF    PSYCHOANALYSIS 

It  will  be  clear  from  the  foregoing  that  the  task  of  the 
psychoanalyst  is  to  bring  into  the  high  light  of  conscious- 
ness the  ideas  or  associations  which  have  been  relegated 
to  the  recesses  of  the  unconscious.  The  sole  clue,  how- 
ever, to  such  repressed  fancies  lies  in  the  symbolic  equiva- 
lents into  which  these  unconscious  ideas  have  been  con- 
verted through  the  process  of  repression.  And  the  source 
of  such  surrogate  symbolizations  is  to  be  sought  in  the 
symptoms  themselves,  in  every  spontaneous,  unguarded 
reaction  of  the  patient,  and,  most  critically  of  all,  in  the 
patient's  dreams.  For  it  is  in  the  drama  of  dream  imagery, 
which  the  mind  enacts  during  sleep,  when  the  sentinels 
standing  guard  at  the  outposts  of  consciousness  grow  lax 
in  their  vigil,  that  these  harpies  of  the  unconscious  most 
easily  escape  durance  and  venture  to  disport  themselves 
with  least  danger  of  surprise. 

Here,  then,  is  our  opportunity  to  take  the  demon  of  the 
unconscious  unawares.  Not  that  this  unconscious  ogre, 
be  it  remembered,  is  wont,  even  in  dreams,  openly  to 
expose  itself,  but  there  are  revealed  in  the  creations  of 
dream  phantasy  traces  of  its  presence  whereby  it  may  be 
tracked  to  its  hiding.  This  tracing  of  the  repressed  in- 
terests contained  in  the  ideas  lying  behind  the  dream 
images  constitutes  the  method  of  dream  analysis,  as  de- 
veloped by  Freud,  and  it  is  the  analysis  of  the  patient's 


CONCEPTIONS  AND  MISCONCEPTIONS    221 

dreams  which  is  by  far  the  most  important  resource  of  the 
psychoanalyst. 

In  Freud's  conception,  the  actual  dream,  as  revealed 
to  consciousness,  that  is,  the  manifest  content  of  the 
dream,  is  but  an  enigmatic  congeries  of  psychic  images — 
a  charade  that  condenses  in  scenic  productions  a  whole 
mass  of  related,  interconnected  meanings  or  dream 
thoughts,  and  it  is  the  latter  which  constitute  the  real  or 
latent  content  of  the  dream.  Dream  analysis  or  dream 
interpretation  consists  precisely  in  reaching  these  con- 
cealed fancies  and  so  correlating  them  in  accordance  with 
precepts  empirically  determined  as  to  render  them  co- 
herent and  significant.  To  do  this  it  is  required  that  the 
patient  retrace  the  mental  threads  out  of  which  he  has 
woven  together  the  elements  of  his  dream  tapestry.  Such 
threads  are  composed  of  links  in  interconnected  chains  of 
associations,  and  it  is  the  task  of  psychoanalysis  to  follow 
these  threads  of  associations  to  their  source,  in  order  to 
reach  the  material  out  of  which  the  dream  images  were 
originally  spun. 

Such  a  proceeding  is  fraught  with  difficulties,  for  ob- 
viously as  the  dream  creation  is  precisely  the  outcome  of 
the  effort  of  consciousness  to  disguise,  and  so  evade,  the 
real  meaning  underlying  the  manifest  dream  elements, 
analysis  involves  a  task  no  less  formidable  than  that  of 
pitting  the  patient  against  his  own  inherent  will.  It  really 
means  setting  the  patient  at  cross  purposes  with  himself 
by  forcing  him  to  face  frankly  the  thoughts  and  wishes 
which  he  has  perhaps  for  a  lifetime  sought  to  repudiate; 
that  is  to  say,  the  ideas  which  have  been  ruthlessly  de- 
barred entrance  into  consciousness  and  which  in  conse- 
quence pursue  their  career  beyond  the  pale  of  appercep- 
tion, manifesting  themselves  subtly  in  the  symptoms  and 
obsessions  characteristic  of  neurotic  states.  These  ideas 
are  one  by  one  readmitted  into  consciousness  and  are 
through  this  procedure  deprived  de  facto  of  the  essential 
motive  of  their  existence. 


222  CONTEMPORARY  SCIENCE 

As  the  analysis  constitutes  per  se  the  entire  system  of 
psychotherapy  introduced  by  Freud,  an  adequate  account 
of  the  psychoanalytic  method  would  entail  a  full  descrip- 
tion of  its  technic.  The  technic  of  psychoanalysis,  how- 
ever, IS  too  varied  to  be  susceptible  of  definite  formula- 
tion. Indeed,  the  technic  of  psychoanalysis  is  too  inti- 
mately bound  up  with  the  delicate  psychologic  rapport 
existing  between  physician  and  patient  to  be  separate 
from  it,  for  each  detail  of  the  patient's  behavior  conveys 
its  own  nuance  of  meaning  that  is  of  the  utmost  import 
to  the  psychoanalyst. 

The  practical  procedure  which  is  followed  in  the  analy- 
sis of  dreams,  however,  may  be  broadly  indicated.  The 
patient,  having  repeated  his  dreams,  is  asked  to  relate 
quite  freely  whatever  occurs  to  his  mind  in  connection 
with  the  different  elements  of  which  the  dream  is  com- 
posed. This  method  Freud  calls  that  of  "free-associa- 
tion.'' From  the  ultimate  ideas  at  which  the  patient  ar- 
rives at  the  end  of  each  of  the  chains  of  associations 
leading  from  the  several  elements  of  the  manifest  dream 
content,  the  physician  is  enabled  to  reconstruct  the  under- 
lying trend  contained  in  the  latent  content  of  the  dream 
and  so  discover  the  patient's  dream  thoughts. 

The  links  in  the  chains  of  associations  do  not  succeed 
each  other  at  regular  intervals,  but  frequently  the  patient 
halts,  showing  signs  of  discomfort  and  unwillingness  to 
continue.  It  is  apparent  that  in  such  instances  the  pa- 
tient's flow  of  thought  is  blocked  by  resistances,  that  is, 
he  has  come  on  a  trend  which  he  has  long  put  away  from 
him  as  distasteful,  as  unfit  to  hold  a  share  in  his  contem- 
porary consciousness.  At  such  crises,  the  patient  must 
be  encouraged  to  continue  without  fear  or  reserve.  He 
is  reminded  that  the  self-criticism  which  interposes  itself 
in  the  current  of  his  spontaneous  associations  tends  to 
thwart  the  course  of  the  analysis  and  to  frustrate  the 
whole  purpose  of  the  procedure.  So  when  he  resumes 
again  the  thread  of  associations,  concentrating  his  atten- 


CONCEPTIONS  AND  MISCONCEPTIONS    223 

tion  anew  on  the  reminiscences  occurring  at  the  point  of 
interruption,  it  is  usual  that  he  will  be  brought  to  reveal 
some  incident  or  trend  of  marked  significance  in  his  affec- 
tive life.  In  other  words,  one  comes  in  such  intervals  on 
psychic  material  which  has  been  submitted  to  the  process 
of  repression  and  which,  with  its  clusters  of  associations, 
constitutes  a  deterring  "complex"  in  the  patient's  psychic 
life. 

In  fairness  it  must  be  said  that  the  psychoanalytic 
method  of  procedure  is  far  simpler  to  set  down  in  writing 
than  to  carry  out  in  actual  practice.  From  the  very  nature 
of  the  neurosis,  with  its  repression  or  rendering  uncon- 
scious of  the  most  vital  trends  in  the  psychic  life  of  the 
individual,  there  are,  of  course,  enormous  habitual  resist- 
ances to  be  overcome.  To  lead  the  patient  to  break 
through  this  habitual  reserve  is  a  task  requiring  the  utmost 
expenditure  of  time,  patience  and  ingenuity  on  the  part  of 
the  physician,  so  that  not  infrequently  hours  are  consumed 
in  arriving  at  the  determination  of  an  objective  statement 
which  it  would  require  but  a  few  minutes  to  set  down  in 
writing. 

Of  course  the  central  interest  in  dream  analysis  lies  in 
Freud's  dynamic  theory  of  dreams.  Freud  teaches  that 
the  basic  factor  in  every  dream  is  an  unconscious  wish 
fulfilment:  that  whatever  the  manifest  content  may  be, 
however  foreign  apparently  to  the  idea  of  a  coveted  pur- 
pose, every  dream  will,  on  adequate  analysis,  reveal  the 
presence  of  a  repressed  wish.  How  totally  dissimilar  in 
their  content  are  the  repressed  wishes  of  the  unconscious 
from  what  we  commonly  accept  as  the  interests  of  our 
conative  life,  how  utterly  abhorrent  to  our  ethical  sensi- 
bilities such  latent  "wishes"  invariably  are,  what,  in  short, 
is  the  real  nature  of  an  unconscious  wish,  in  the  sense  of 
Freud,  may  be  gathered  only  from  a  thorough  study  of 
Freud's  dynamic  psychology  of  the  unconscious  as  con- 
tained in  his  major  work  "Die  Traumdeutung."  ^     It  is 

^  Freud :  Die  Traumdeutung,  Vienna,  Deuticke,  1910,  transla- 
tion of  A.  A.  Brill. 


224  CONTEMPORARY  SCIENCE 

here  alone  that  one  is  enabled  to  comprehend  the  very 
original  and  revolutionary  conceptions  on  which  Freud 
bases  his  theory  of  the  unconscious  and  in  which  he  elabo- 
rates the  principles  underlying  his  searching  study  of  the 
biology  of  mind. 

Next  in  importance  to  dream  analysis  is  the  association 
experiment  which  Jung  of  Zurich  has  adapted  to  practical 
psychoanalytic  application.^  The  association  experiment  is 
useful  chiefly  as  an  instrument  of  diagnosis  and  for  the 
purpose  of  a  long-continued  study  of  some  specific  prob- 
lem, as  the  differences  of  reaction  types.  But  it  is  also 
most  valuable  to  the  student  in  beginning  psychoanalysis 
as  a  means  of  obtaining  a  preliminary  survey  of  the  gen- 
eral reaction  of  the  patient  and  of  opening  the  way 
toward  gaining  insight  into  his  unconscious  mental  proc- 
esses. 

The  association  experiment  has  three  chief  advantages : 
First,  it  affords  a  direct  avenue  to  the  patient's  repressed 
interests ;  second,  it  offers  access  to  such  repressed  spheres 
of  affectivity  in  spite  of  the  patient's  own  unyielding  re- 
sistances, and,  third,  it  affords  us  a  means  of  investigation 
which  includes  in  it  the  conditions  of  an  objective  control 
so  essential  to  an  exact  experimental  study  of  the  data 
required  in  comparative  psychologic  tests. 

In  arrangement  and  actuation  the  association  experi- 
ment is  very  simple.  The  idea  of  the  test  is  this :  Every 
word  represents  for  each  person  a  psychologic  situation. 
This  may  have,  according  to  individual  circumstances,  an 
accent  of  greater  or  less  emotional  value.  To  say  that  a 
word  possesses  an  emotional  value  is  the  equivalent  of 
saying  that  it  makes  a  deep  impression  on  the  psychic 
organism,  that  is,  that  it  stirs  a  strong  wave  of  response 
in  the  consciousness  into  which  it  falls. 

Manifestly,  if  the  length  of  such  emotional  wave  may 
be  estimated,  we  have  obtained  a  measure  of  the  relative 

«  Jung,  C.  J. :  Diagnostische  Associationsstudien, 


CONCEPTIONS  AND  MISCONCEPTIONS    225 

strength  of  the  emotional  tone  represented  by  it.  This  is 
precisely  the  result  which  is  affected  by  the  conditions  of 
the  association  experiment. 

A  series  of  words  called  test  words,  usually  100,  are 
repeated  to  the  patient,  who  is  required  to  respond  at  once 
with  the  first  word  associating  itself  in  his  mind  with  the 
test  word  given.  By  measuring  with  a  stop  watch,  re- 
cording fifths  of  a  second,  the  interval  occurring  between 
the  stimulus  (the  calling  of  test  word)  and  the  reaction 
(the  patient's  response),  a  mathematical  estimate  is  given 
of  the  relative  emotional  value  of  the  situation  recalled 
by  the  test  word  in  question ;  for  the  more  profoundly  the 
consciousness  of  the  patient  is  stirred,  the  longer  will  be 
the  interval  required  in  order  to  return  to  the  mechanical 
routine  of  response  required  by  the  concrete  conditions  of 
the  experiment. 

Hence,  having  obtained  the  length  of  the  patient's 
probable  average  of  reaction  time,  any  marked  excess  of 
this  interval  indicates  the  presence  of  a  significant  remi- 
niscence, that  is,  of  an  underlying  complex.  A  marked 
variation  in  the  length  of  reaction  time  is,  then,  the  most 
important  of  the  complex  indicators. 

A  further  aid  in  unearthing  the  hidden  complexes  is 
that  of  obtaining  the  patient's  "reproductions,"  that  is, 
having  obtained  his  responses  to  the  series  of  stimulus 
words,  to  test  his  memory  of  each  of  his  responses  by 
again  repeating  the  test  words.  In  this  procedure  a  wrong 
reproduction  or  failure  to  recall  at  all  the  original  reaction 
word  is  indicative  of  a  complex  having  been  stirred.  Here 
again  the  excess  of  the  affect  carries  the  mind  of  the 
patient  from  the  immediate  verbal  image  to  some  inti- 
mately associated  impression,  and  the  significance  of  the 
reaction  word  as  such  is  lost  in  the  greater  emphasis  of 
the  remembrance  awakened  by  it. 

Still  a  further  complex  indicator  consists  in  the  succes- 
sive decrease  of  the  heightened  interval  of  reaction  time 
effecting  the  three  or  four  immediately  subsequent  reac- 


226  CONTEMPORARY  SCIENCE 

tions.  To  this  species  of  complex  indicator  Jung  has 
given  the  name  "perseveration." 

The  frequent  recurrence  of  the  same  reaction  word 
throughout  the  experiment,  the  assimilation  of  the  test 
word  in  an  unusual  sense,  repeating  the  stimulus  word 
before  reacting,  replying  with  more  than  a  single  word, 
offering  explanations,  etc.,  are  among  the  many  additional 
indications  that  a  complex  has  been  excited. 

Such  are  the  chief  means  affording  a  clue  to  the  lines 
along  which  the  analysis  may  most  judiciously  direct  its 
inquiry  and  so  contribute  to  effect  the  release  and  thorough 
ventilation  of  the  repressed  affects  which  are  responsible 
for  the  inner  psychic  disharmony. 

It  is  thus  that  the  physician  succeeds  in  establishing  a 
synthesis  amid  the  discordant,  mutually  exclusive  ele- 
ments of  the  personality.  It  is  thus  that  the  psychic  ten- 
sion due  to  the  mental  conflict  is  eliminated  and  the  dis- 
sociated elements  of  the  ego  are  brought  together  in  a 
simple  unitary  stream  of  consciousness. 

Such  is  the  treatment  of  psychic  disorders  by  the  method 
of  psychoanalysis.  The  statement  given  here  affords  but 
the  merest  hint  of  the  full  import  of  the  method.  This  is 
long  and  laborious,  often  entailing  in  actual  practice  many 
months  for  the  adequate  analysis  of  a  single  case.  To 
gain  anything  like  a  commensurate  idea  of  the  full  sig- 
nificance of  the  psychoanalytic  method,  one  must  put  him- 
self in  touch  with  Freud's  conceptions  of  the  unconscious 
as  presented  in  his  writings.  In  his  various  contributions 
to  the  literature  of  psychopathology,  Freud  has  presented 
an  account  of  the  system  of  psychology  on  which  he  bases 
his  explanation  of  the  essential  processes  underlying  neu- 
rotic disorders  and  in  which  he  defines  the  rationale  of 
the  psychoanalytic  method  of  treatment. 

USES    OF   PSYCHOANALYSIS 

While,  in  my  opinion,  the  discoveries  made  by  Freud 
through  his  long  and  laborious  investigations  are  as  sound 


CONCEPTIONS  AND  MISCONCEPTIONS    227 

scientifically  and  as  important  economically  as  any  in  the 
history  of  modern  medicine,  I  do  not  by  any  means  regard 
psychoanalysis  as  a  universal  panacea  for  nervous  dis- 
orders, but  on  the  contrary  consider  it  as  the  particular 
method  of  psychotherapy  that  is  most  restricted  in  its 
possibilities  of  application,^  a  reflection,  however,  which 
is  rather  comforting  than  otherwise  when  we  consider  the 
length  of  time  required — frequently,  as  I  have  said,  as 
much  as  an  hour  daily  for  weeks  and  even  months — for 
the  adequate  analysis  of  a  single  case.  This  being  true, 
it  seems  a  fortunate  circumstance  that  psychoanalysis  is 
not  the  suitable  method  in  all  cases — that  other  and  sim- 
pler methods  of  psychotherapy  are  applicable  in  many 
types  and  degrees  of  nervous  manifestations,  and  even  if 
sometimes  unscientific,  they  are  at  least  efifective  for  the 
ignorant  masses  to  whom  they  are  applicable. 

The  fact  is  that  psychoanalysis  is  practically  adapted  to 
only  a  few  persons,  but  those  few  belong,  generally  speak- 
ing, to  the  most  educated  classes  and  are  precisely  those 
personalities  who,  from  the  nature  of  the  conditions  of 
the  onset  of  a  neurosis,  are  the  most  sensitive,  highly  de- 
veloped and  worth  while  among  us,  and  whose  re-educa- 
tion through  self-analysis  will  be  most  far-reaching  in  its 
influence  on  the  body  social. 

Psychoanalysis  can  never  hope  to  become  popular  for 
the  reason  that  it  is  honest.  It  does  not  flatter  or  cajole 
the  patient  or  seek  to  appease  him  with  subtle  blandish- 
ments ;  on  the  contrary,  it  mercilessly  thwarts  and  assails. 
him.  The  mawkish  and  artificial  will  find  in  it  little  unc- 
tion of  their  boredom.  Psychoanalysis  oflfers  nothing  bril- 
liant or  spectacular,  but,  being  a  robust,  uncompromising^ 
method  of  scientific  investigation,  it  proceeds  in  the  la- 
borious, unobtrusive  manner  of  all  earnest  research,  and 
is  adapted  to  the  needs  of  only  earnest  and  intelligent  men 
and  women. 

■^  Freud  has  himself  been  most  explicit  in  the  practical  limita- 
tions he  has  recognized  in  the  use  of  the  psychoanaljrtic  methods 


228  CONTEMPORARY  SCIENCE 

Though  lacking  in  frills,  the  method  is  not  without  its 
practical  compensations.  One  need  not  be  irresistible  to 
i)e  a  psychoanalyst.  In  psychoanalysis  "personality  "  is  no 
asset.  The  method  places  no  premium  on  the  personal 
charms  of  the  physician. 

The  misconception  concerning  psychoanalysis  which 
seems  to  me  of  all  the  most  unfortunate  is  the  view  that 
there  exists  an  inherent  opposition  between  the  principles 
of  psychoanalysis  and  those  of  experimental  psychology. 
On  the  contrary,  the  psychoanalyst  of  far  perspectives  can 
hardly  fail  to  recognize  the  possibilities  of  mutual  gain  in 
the  complementary  positions  which  these  two  departments 
of  research  occupy  in  relation  to  one  another,  nor  can 
he  fail  to  see  the  opportunity  he  has  in  the  objective  con- 
trols of  the  experimental  method  for  the  substantiation  of 
his  results.  Nothing,  it  seems,  to  me,  can  more  certainly 
cripple  the  researches  of  the  psychoanalyst  than  this  very 
fundamental  misapprehension. 

I  believe  William  James  once  said  that  when  any  dis- 
covery is  newly  given  to  science  the  cry  at  first  is  that  it 
is  not  true,  but  that  later,  as  the  truth  of  the  new  theory 
hecomes  manifest,  this  attitude  is  replaced  by  the  admis- 
sion, "  Yes,  it  is  true,  but  /  discovered  it."  Now  that 
psychoanalysis  is  entering  this  latter  phase  of  its  career, 
there  begin  to  appear  various  bogus  psychoanalytic  pro- 
cedures which  are  in  truth  mere  travesties  on  the  original 
method  by  Freud,  and  we  need  be  on  our  guard  against 
the  cunning  decoys  of  such  spurious  artifices. 

We  shall  do  well,  therefore,  to  discriminate  between 
psychoanalysis  as  represented  in  the  systematic,  laborious, 
time-consuming  method  of  psychotherapeutic  research  in- 
troduced by  Sigmund  Freud — a  method  imbued  through- 
out with  the  spirit  and  ideals  of  the  laboratory — and  the 
pseudopsychoanalytic  substitutes  which  pervert  Freud's 
method  to  sensational  uses.  Psychoanalysis  proper  is 
wholly  incompatible  with  the  business  of  medicine.  The 
hurrying  practitioners  who  say  that  they  use  psychoanaly- 


CONCEPTIONS  AND  MISCONCEPTIONS    229 

SIS  as  occasion  arises,  as  though  they  kept  it  on  a  shelf  in 
bottles,  simply  fail  to  understand  the  first  principles  of 
the  method ;  for  psychoanalysis  is  not  a  tablet  but  a  system. 
It  is  not  to  be  summoned  by  caprice  or  expedience  but 
must  be  acquired  by  careful  study  and  training,  and  above 
all  by  the  exacting  discipline  of  a  thoroughgoing  self- 
analysis. 


EINSTEIN'S  LAW  OF  GRAVITATION 

(Address  of  the  President  of  the  American  Psy- 
sical  Society,  St.  Louis,  1919) 

BY 

J.  S.  Ames 
Professor  of  Physics  Johns  Hopkins  University 

In  the  treatment  of  MaxwelFs  equations  of  the  electro- 
magnetic field,  several  investigators  realized  the  impor- 
tance of  deducing  the  form  of  the  equations  when  applied 
to  a  system  moving  with  a  uniform  velocity.  One  object 
of  such  an  investigation  would  be  to  determine  such  a  set 
of  transformation  formulae  as  would  leave  the  mathemati- 
cal form  of  the  equations  unaltered.  The  necessary  re- 
lations between  the  new  space-coordinates,  those  applying 
to  the  moving  system,  and  the  original  set  were,  of  course, 
obvious ;  and  elementary  methods  led  to  the  deduction  of 
a  new  variable  which  should  replace  the  time  coordinate. 
This  step  was  taken  by  Lorentz  and  also,  I  believe,  by 
Larmor  and  by  Voigt. 

Lorentz'  paper  on  this  subject  appeared  in  the  Pro- 
ceedings of  the  Amsterdam  Academy  in  1904.  In  the 
following  year  there  was  published  in  the  Annalen  der 
Physik  a  paper  by  Einstein,  written  without  any  knowl- 
edge of  the  work  of  Lorentz,  in  which  he  arrived  at  the 
same  transformation  equations  as  did  the  latter,  but  with 
an  entirely  different  and  fundamentally  new  interpreta- 
tion. Einstein  called  attention  in  his  paper  to  the  lack  of 
definiteness  in  the  concepts  of  time  and  space,  as  ordi- 

230 


EINSTEIN'S  LAW  OF  GRAVITATION      231 

narily  stated  and  used.  He  analyzed  clearly  the  definitions 
and  postulates  which  were  necessary  before  one  could 
speak  with  exactness  of  a  length  or  of  an  interval  of 
time.  He  disposed  forever  of  the  propriety  of  speaking 
of  the  "true"  length  of  a  rod  or  of  the  "true''  duration  01 
time,  showing,  in  fact,  that  the  numerical  values  which  we 
attach  to  lengths  or  intervals  of  time  depend  upon  the 
definitions  and  postulates  which  we  adopt.  The  words 
"absolute"  space  or  time  intervals  are  devoid  of  meaning. 
As  an  illustration  of  what  is  meant  Einstein  discussed  two 
possible  ways  of  measuring  the  length  of  a  rod  when  it  is 
moving  in  the  direction  of  its  own  length  with  a  uniform 
velocity,  that  is,  after  having  adopted  a  scale  of  length, 
two  ways  of  assigning  a  number  to  the  length  of  the  rod 
concerned.  One  method  is  to  imagine  the  observer  mov- 
ing with  the  rod,  applying  along  its  length  the  measuring 
scale,  and  reading  off  the  positions  of  the  ends  of  the  rod. 
Another  method  would  be  to  have  two  observers  at  rest 
on  the  body  with  reference  to  which  the  rod  has  the  uni- 
form velocity,  so  stationed  along  the  line  of  motion  of  the 
rod  that  as  the  rod  moves  past  them  they  can  note  simul- 
taneously on  a  stationary  measuring  scale  the  positions  of 
the  two  ends  of  the  rod.  Einstein  showed  that,  accepting 
two  postulates  which  need  no  defense  at  this  time,  the  two 
methods  of  measurements  would  lead  to  different  numeri- 
cal values,  and,  further,  that  the  divergence  of  the  two 
results  would  increase  as  the  velocity  of  the  rod  was  in' 
creased. 

In  assigning  a  number,  therefore,  to  the  length  of  a 
moving  rod,  one  must  make  a  choice  of  the  method  to  be 
used  in  measuring  it.  Obviously  the  preferable  method 
is  to  agree  that  the  observer  shall  move  with  the  rod, 
carrying  his  measuring  instrument  with  him.  This  dis- 
poses of  the  problem  of  measuring  space  relations.  The 
observed  fact  that,  if  we  measure  the  length  of  the  rod  on 
different  days,  or  when  the  rod  is  lying  in  different  posi- 
tions, we  always  obtain  the  same  value  offers  no  informa- 


232  CONTEMPORARY  SCIENCE 

tion  concerning  the  "real"  length  of  the  rod.  It  may  have 
changed,  or  it  may  not.  It  must  always  be  remembered 
that  measurement  of  the  length  of  a  rod  is  simply  a  process 
of  comparison  between  it  and  an  arbitrary  standard,  e.g., 
a  meter-rod  or  yard-stick.  In  regard  to  the  problem  of 
assigning  numbers  to  intervals  of  time,  it  must  be  borne 
in  mind  that,  strictly  speaking,  we  do  not  "measure"  such 
intervals,  i,e,,  that  we  do  not  select  a  unit  interval  of  time 
and  find  how  many  times  it  is  contained  in  the  interval 
in  question.  (Similarly,  we  do  not  "measure"  the  pitch 
of  a  sound  or  the  temperature  of  a  room.) 

Our  practical  instruments  for  assigning  numbers  to 
time-intervals  depend  in  the  main  upon  our  agreeing  to 
believe  that  a  pendulum  swings  in  a  perfectly  uniform 
manner,  each  vibration  taking  the  same  time  as  the  next 
one.  Of  course  we  cannot  prove  that  this  is  true,  it  is, 
strictly  speaking,  a  definition  of  what  we  mean  by  equal 
intervals  of  time ;  and  it  is  not  a  particularly  good  defini- 
tion at  that.  Its  limitations  are  sufficiently  obvious.  The 
best  way  to  proceed  is  to  consider  the  concept  of  uniform 
velocity,  and  then,  using  the  idea  of  some  entity  having 
such  a  uniform  velocity,  to  define  equal  intervals  of  time 
as  such  intervals  as  are  required  for  the  entity  to  traverse 
equal  lengths.  These  last  we  have  already  defined.  What 
is  required  in  addition  is  to  adopt  some  moving  entity  as 
giving  our  definition  of  uniform  velocity.  Considering 
our  known  universe  it  is  self-evident  that  we  should  choose 
in  our  definition  of  uniform  velocity  the  velocity  of  light, 
since  this  selection  could  be  made  by  an  observer  anywhere 
in  our  universe.  Having  agreed  then  to  illustrate  by  the 
words  "uniform  velocity"  that  of  light,  our  definition  of 
equal  intervals  of  time  is  complete.  This  implies,  of 
course,  that  there  is  no  uncertainty  on  our  part  as  to  the 
fact  that  the  velocity  of  light  always  has  the  same  value 
at  any  one  point  in  the  universe  to  any  observer,  quite  re- 
gardless of  the  source  of  light.  In  other  words,  the  pos- 
tulate that  this  is  true  underlies  our  definition. 


EINSTEIN^S  LAW  OF  GRAVITATION      233 

Following  this  method  Einstein  developed  a  system  of 
measuring  both  space  and  time  intervals.  As  a  matter 
of  fact  his  system  is  identically  that  which  we  use  in  daily 
life  with  reference  to  events  here  on  the  earth.  He  further 
showed  that  if  a  man  were  to  measure  the  length  of  a 
rod,  for  instance,  on  the  earth  and  then  were  able  to  carry 
the  rod  and  his  measuring  apparatus  to  Mars,  the  sun,  or 
to  Arcturus  he  would  obtain  the  same  numerical  value 
for  the  length  in  all  places  and  at  all  times.  This  doesn't 
mean  that  any  statement  is  implied  as  to  whether  the 
length  of  the  rod  has  remained  unchanged  or  not;  such 
words  do  not  have  any  meaning — remember  that  we  can- 
not speak  of  true  length.  It  is  thus  clear  that  an  observer 
living  on  the  earth  would  have  a  definite  system  of  units 
in  terms  of  which  to  express  space  and  time  intervals,  i.e., 
he  would  have  a  definite  system  of  space  coordinates 
(^,  y>  ^)  and  a  definite  time  coordinate  (t)  ;  and  simi- 
larly an  observer  living  on  Mars  would  have  his  system 
of  coordinates  (x,  y,  z ,  f).  Provided  that  one  observer 
has  a  definite  uniform  velocity  with  reference  to  the  other, 
it  is  a  comparatively  simple  matter  to  deduce  the  mathe- 
matical relations  between  the  two  sets  of  coordinates. 
When  Einstein  did  this,  he  arrived  at  the  same  transfor- 
mation formulae  as  those  used  by  Lorentz  in  his  develop- 
ment of  Maxwell's  equations.  The  latter  had  shown  that, 
using  this  formulae,  the  form  of  the  laws  for  all  electro- 
magnetic phenomena  maintained  the  same  form ;  so  Ein- 
stein's method  proves  that  using  his  system  of  measure- 
ment an  observer,  anywhere  in  the  universe,  would  as  the 
result  of  his  own  investigation  of  electromagnetic  phenom- 
ena arrive  at  the  same  mathematical  statement  of  them  as 
any  other  observer,  provided  only  that  the  relative  veloc- 
ity of  the  two  observers  was  uniform. 

Einstein  discussed  many  other  most  important  questions 
at  this  time;  but  it  is  not  necessary  to  refer  to  them  in 
connection  with  the  present  subject.  So  far  as  this  is 
concerned,  the  next  important  step  to  note  is  that  taken  in 


234  CONTEMPORARY  SCIENCE 

the  famous  address  of  Minkowski,  in  1908,  on  the  sub- 
ject of  "Space  and  Time."  It  would  be  difficult  to  over- 
state the  importance  of  the  concepts  advanced  by  Minkow- 
ski. They  marked  the  beginning  of  a  new  period  in  the 
philosophy  of  physics.  I  shall  not  attempt  to  explain  his 
ideas  in  detail,  but  shall  confine  myself  to  a  few  general 
statements.  His  point  of  view  and  his  line  of  develop- 
ment of  the  theme  are  absolutely  different  from  those  of 
Lorentz  or  of  Einstein;  but  in  the  end  he  makes  use  of 
the  same  transformation  formulae.  His  great  contribution 
consists  in  giving  us  a  new  geometrical  picture  of  their 
meaning.  It  is  scarcely  fair  to  call  Minkowski's  develop- 
ment a  picture ;  for  to  us  a  picture  can  never  have  more 
than  three  dimensions,  our  senses  limit  us ;  while  his  pic- 
ture calls  for  perception  of  four  dimensions.  It  is  this 
fact  that  renders  any  even  semi-popular  discussion  of 
Minkowski's  work  so  impossible.  We  can  all  see  that 
for  us  to  describe  any  event  a  knowledge  of  four  co- 
ordinates is  necessary,  three  for  the  space  specification  and 
one  for  the  time.  A  complete  picture  could  be  given  then 
by  a  point  in  four  dimensions.  All  four  coordinates  are 
necessary :  we  never  observe  an  event  except  at  a  certain 
time,  and  we  never  observe  an  instant  of  time  except  with 
reference  to  space.  Discussing  the  laws  of  electromagnetic 
phenomena,  Minkowski  showed  how  in  a  space  of  four  di- 
mensions, by  a  suitable  definition  of  axes,  the  mathemati- 
cal transformation  of  Lorentz  and  Einstein  could  be  de- 
scribed by  a  rotation  of  the  set  of  axes.  We  are  all 
accustomed  to  a  rotation  of  our  ordinary  cartesian  set  of 
axes  describing  the  position  of  a  point.  We  ordinarily 
choose  our  axes  at  any  location  on  the  earth  as  follows : 
one  vertical,  one  east  and  west,  one  north  and  south.  So 
if  we  move  from  any  one  laboratory  to  another,  we  change 
our  axes ;  they  are  always  orthogonal,  but  in  moving  from 
place  to  place  there  is  a  rotation.  Similarly,  Minkowski 
showed  that  if  we  choose  four  orthogonal  axes  at  any 
point  on  the  earth,  according  to  his  method,  to  represent 


EINSTEIN'S  LAW  OF  GRAVITATION      235 

a  space-time  point  using  the  method  of  measuring  space 
and  time  intervals  as  outlined  by  Einstein;  and,  if  an 
observer  on  Arcturus  used  a  similar  set  of  axes  and  the 
method  of  measurement  which  he  naturally  would,  the 
set  of  axes  of  the  latter  could  be  obtained  from  those  of 
the  observer  on  the  earth  by  a  pure  rotation  (and  naturally 
a  transfer  of  the  origin).  This  is  a  beautiful  geometrical 
result.  To  complete  my  statement  of  the  method,  I  must 
add  that  instead  of  using  as  his  fourth  axis  one  along 
which  numerical  values  of  time  are  laid  off,  Minkowski 
defined  his  fourth  coordinate  as  the  product  of  time  and 
the  imaginary  constant,  the  square  root  of  minus  one. 
This  introduction  of  imaginary  quantities  might  be  ex- 
pected, possibly,  to  introduce  difficulties ;  but,  in  reality,  it 
is  the  very  essence  of  the  simplicity  of  the  geometrical 
description  just  given  of  the  rotation  of  the  sets  of  axes. 
It  thus  appears  that  different  observers  situated  at  dif- 
ferent points  in  the  universe  would  each  have  their  own 
set  of  axes,  all  different,  yet  all  connected  by  the  fact 
that  any  one  can  be  rotated  so  as  to  coincide  with  any 
other.  This  means  that  there  is  no  one  direction  in  the 
four  dimensional  space  that  corresponds  to  time  for  all 
observers.  Just  as  with  reference  to  the  earth  there  is  no 
direction  which  can  be  called  vertical  for  all  observers 
living  on  the  earth.  In  the  sense  of  an  absolute  meaning 
the  words  "up  and  down,"  "before  and  after,"  "sooner  or 
later,"  are  entirely  meaningless. 

This  concept  of  Minkowski's  may  be  made  clearer,  per- 
haps, by  the  following  process  of  thought.  If  we  take  a 
section  through  our  three  dimensional  space,  we  have  a 
plane,  i.e.,  a  two-dimensional  space.  Similarly,  if  a  sec- 
tion is  made  through  a  four-dimensional  space,  one  of 
three  dimensions  is  obtained.  Thus,  for  an  observer  on 
the  earth  a  definite  section  of  Minkowski's  four  dimen- 
sional space  will  give  us  our  ordinary  three-dimensional 
one;  so  that  this  section  will,  as  it  were,  break  up  Min- 
kowski's space  into  our  space  and  give  us  our  ordinary 


236  CONTEMPORARY  SCIENCE 

time.  Similarly,  a  different  section  would  have  to  be  used 
for  the  observer  on  Arcturus ;  but  by  a  suitable  selection 
he  would  get  his  own  familiar  three-dimensional  space 
and  his  own  time.  Thus  the  space  defined  by  Minkowski 
is  completely  isotrophic  in  reference  to  measured  lengths 
and  times,  there  is  absolutely  no  difference  between  any 
two  directions  in  an  absolute  sense;  for  any  particular 
observer,  of  course,  a  particular  section  will  cause  the 
space  to  fall  apart  so  as  to  suit  his  habits  of  measurement ; 
any  section,  however,  taken  at  random  will  do  the  same 
thing  for  some  observer  somewhere.  From  another  point 
of  view,  that  of  Lorentz  and  Einstein,  it  is  obvious  that, 
since  this  four  dimensional  space  is  isotropic,  the  expres- 
sion of  the  laws  of  electromagnetic  phenomena  take  iden- 
tical mathematical  forms  when  expressed  by  any  observer. 
The  question,  of  course,  must  be  raised  as  to  what  can 
be  said  in  regard  to  phenomena  which  so  far  as  we  know 
do  not  have  an  electromagnetic  origin.  In  particular  what 
can  be  done  with  respect  to  gravitational  phenomena  ?  Be- 
fore, however,  showing  how  this  problem  was  attacked 
by  Einstein;  and  the  fact  that  the  subject  of  my  address 
is  Einstein's  work  on  gravitation  shows  that  ultimately  I 
shall  explain  this,  I  must  emphasize  another  feature  of 
Minkowski's  geometry.  To  describe  the  space-time  char- 
acteristics of  any  event  a  point,  defined  by  its  four  co- 
ordinates, is  sufficient ;  so,  if  one  observes  the  life-history 
of  any  entity,  e.g.,  2l  particle  of  matter,  a  light-wave,  etc., 
he  observes  a  sequence  of  points  in  the  space-time  conti- 
nuum; that  is,  the  life-history  of  any  entity  is  described 
fully  by  a  line  in  this  space.  Such  a  line  was  called  by 
Minkowski  a  "world-line."  Further,  from  a  different 
point  of  view,  all  of  our  observations  of  nature  are  in 
reality  observations  of  coincidences,  e.g.,  if  one  reads  a 
thermometer,  what  he  does  is  to  note  the  coincidence  of 
the  end  of  the  column  of  mercury  with  a  certain  scale 
division  on  the  thermometer  tube.  In  other  words,  think- 
ing of  the  world-line  of  the  end  of  the  mercury  column 


EINSTEIN'S  LAW  OF  GRAVITATION      237 

and  the  world-line  of  the  scale  division,  what  we  have 
observed  was  the  intersection  or  crossing  of  these  lines. 
In  a  similar  manner  any  observation  may  be  analyzed; 
and  remembering  that  light  rays,  a  point  on  the  retina 
of  the  eye,  etc.,  all  have  their  world  lines,  it  will  be  recog- 
nized that  it  is  a  perfectly  accurate  statement  to  say  that 
every  observation  is  the  perception  of  the  intersection  of 
world-lines.  Further,  since  all  we  know  of  a  world-line 
is  the  result  of  observations,  it  is  evident  that  we  do  not 
know  a  world-line  as  a  continuous  series  of  points,  but 
simply  as  a  series  of  discontinuous  points,  each  point 
being  where  the  particular  world-line  in  question  is 
crossed  by  another  world-line. 

It  is  clear,  moreover,  that  for  the  description  of  a 
world-line  we  are  not  limited  to  the  particular  set  of  four 
orthogonal  axes  adopted  by  Minkowski.  We  can  choose 
any  set  of  four-dimensional  axes  we  wish.  It  is  further 
evident  that  the  mathematical  expression  for  the  coinci- 
dence of  two  points  is  absolutely  independent  of  our  se- 
lection of  reference  axes.  If  we  change  our  axes,  we  will 
change  the  coordinates  of  both  points  simultaneously,  so 
that  the  question  of  axes  ceases  to  be  of  interest.  But 
our  so-called  laws  of  nature  are  nothing  but  descriptions 
in  mathematical  language  of  our  observations ;  we  observe 
only  coincidences ;  a  sequence  of  coincidences  when  put 
in  mathematical  terms  takes  a  form  which  is  independent 
of  the  selection  of  reference  axes ;  therefore  the  mathe- 
matical expression  of  our  laws  of  nature,  of  every  char- 
acter, must  be  such  that  their  form  does  not  change  if  we 
make  a  transformation  of  axes.  This  is  a  simple  but  far- 
reaching  deduction. 

There  is  a  geometrical  method  of  picturing  the  effect 
of  a  change  of  axes  of  reference,  i.e,,  of  a  mathematical 
transformation.  To  a  man  in  a  railway  coach  the  path  of 
a  drop  of  water  does  not  appear  vertical,  i.e.,  it  is  not 
parallel  to  the  edge  of  the  window;  still  less  so  does  it 
appear  vertical  to  a  man  performing  maneuvers  in  an 


238  CONTEMPORARY  SCIENCE 

airplane.  This  means  that  whereas  with  reference  to 
axes  fixed  to  the  earth  the  path  of  the  drop  is  vertical; 
with  reference  to  other  axes,  the  path  is  not.  Or,  stating 
the  conclusion  in  general  language,  changing  the  axes  of 
reference  (or  effecting  a  mathematical  transformation) 
in  general  changes  the  shape  of  any  line.  If  one  imagines 
the  Hne  forming  a  part  of  the  space,  it  is  evident  that  if 
the  space  is  deformed  by  compression  or  expansion  the 
shape  of  the  line  is  changed,  and  if  sufficient  care  is  take;p 
it  is  clearly  possible,  by  deforming  the  space,  to  make  the 
line  take  any  shape  desired,  or  better  stated,  any  shape 
^ecified  by  the  previous  change  of  axes.  It  is  thus  pos- 
sible to  picture  a  mathematical  transformation  as  a  defor- 
mation of  space.  Thus  I  can  draw  a  line  on  a  sheet  of 
paper  or  of  rubber  and  by  bending  and  stretching  the 
sheet,  I  can  make  the  line  assume  a  great  variety  of 
shapes;  each  of  these  new  shapes  is  a  picture  of  a  suit- 
able transformation. 

Now,  consider  world-lines  in  our  four  dimensional 
space.  The  complete  record  of  all  our  knowledge  is  a 
series  of  sequences  of  intersections  of  such  lines.  By 
analogy  I  can  draw  in  ordinary  space  a  great  number  of 
intersecting  lines  on  a  sheet  of  rubber ;  I  can  then  bend 
and  deform  the  sheet  to  please  myself ;  by  so  doing  I  do 
not  introduce  any  new  intersections  nor  do  I  alter  in  the 
least  the  sequence  of  intersections.  So  in  the  space  of  our 
world-lines,  the  space  may  be  deformed  in  any  imaginable 
manner  without  introducing  any  new  intersections  or 
changing  the  sequence  of  the  existing  intersections.  It  is 
this  sequence  which  gives  us  the  mathematical  expression 
of  our  so-called  experimental  laws ;  a  deformation  of  our 
space  is  equivalent  mathematically  to  a  transformation 
of  axes,  consequently  we  see  why  it  is  that  the  form  of 
our  laws  must  be  the  same  when  referred  to  any  and  all 
sets  of  axes,  that  is,  must  remain  unaltered  by  any  mathe- 
matical transformation. 

Now,  at  last  we  come  to  gravitation.    We  can  not  imag- 


EINSTEIN'S  LAW  OF  GRAVITATION      239 

ine  any  world-line  simpler  than  that  of  a  particle  of 
matter  left  to  itself;  we  shall  therefore  call  it  a  "straight" 
line.  Our  experience  is  that  two  particles  of  matter  at- 
tract one  another.  Expressed  in  terms  of  world-lines, 
this  means  that,  if  the  world-lines  of  two  isolated  particles 
come  near  each  other,  the  lines,  instead  of  being  straight, 
will  be  deflected  or  bent  in  towards  each  other.  The 
world-line  of  any  one  particle  is  therefore  deformed ;  and 
we  have  just  seen  that  a  deformation  is  the  equivalent  of 
a  mathematical  transformation.  In  other  words,  for  any 
one  particle  it  is  possible  to  replace  the  effect  of  a  gravi- 
tational field  at  any  instant  by  a  mathematical  transforma- 
tion of  axes.  The  statement  that  this  is  always  possible 
for  any  particle  at  any  instant  is  Einstein's  famous  "Prin- 
ciple of  Equivalence." 

Let  us  rest  for  a  moment,  while  I  call  attention  to  a  most 
interesting  coincidence,  not  to  be  thought  of  as  an  inter- 
section of  world-lines.  It  is  said  that  Newton's  thoughts 
were  directed  to  the  observation  of  gravitational  phe- 
nomena by  an  apple  falling  on  his  head ;  from  this  striking 
event  he  passed  by  natural  steps  to  a  consideration  of  the 
universality  of  gravitation.  Einstein  in  describing  his 
mental  process  in  the  evolution  of  his  law  of  gravitation 
says  that  his  attention  was  called  to  a  new  point  of  view 
by  discussing  his  experiences  with  a  man  whose  fall  from 
a  high  building  he  had  just  witnessed.  The  man  fortu- 
nately suffered  no  serious  injuries  and  assured  Einstein 
that  in  the  course  of  his  fall  he  had  not  been  conscious  in 
the  least  of  any  pull  downward  on  his  body.  In  mathe- 
matical language,  with  reference  to  axes  moving  with  the 
man  the  force  of  gravity  had  disappeared.  This  is  a  case 
where  by  the  transfer  of  the  axes  from  the  earth  itself  to 
the  man,  the  force  of  the  gravitational  field  is  annulled. 
The  converse  change  of  axes  from  the  falling  man  to  a 
point  on  the  earth  could  be  considered  as  introducing  the 
force  of  gravity  into  the  equations  of  motion.  Another 
illustration  of  the  introduction  into  our  equations  of  a 


240  CONTEMPORARY  SCIENCE 

force  by  means  of  a  change  of  axes  is  furnished  by  the 
ordinary  treatment  of  a  body  in  uniform  rotation  about 
an  axis.  For  instance,  in  the  case  of  a  so-called  conical 
pendulum,  that  is,  the  motion  of  a  bob  suspended  from 
a  fixed  point  by  a  string,  which  is  so  set  in  motion  that 
the  bob  describes  a  horizontal  circle  and  the  string  there- 
fore describes  a  circular  cone,  if  we  transfer  our  axes 
from  the  earth  and  have  them  rotate  around  the  vertical 
line  through  the  fixed  point  with  the  same  angular  veloc- 
ity as  the  bob,  it  is  necessary  to  introduce  into  our  equa- 
tions of  motion  a  fictitious  "force"  cialled  the  centrifugal 
force.  No  one  ever  thinks  of  this  force  other  than  as  a 
mathematical  quantity  introduced  into  the  equations  for 
the  sake  of  simplicity  of  treatment;  no  physical  meaning 
IS  attached  to  it.  Why  should  there  be  to  any  other  so- 
called  "force,"  which,  like  centrifugal  force,  is  independ- 
ent of  the  nature  of  the  matter?  Again,  here  on  the  earth 
our  sensation  of  weight  is  interpreted  mathematically  by 
combining  expressions  for  centrifugal  force  and  gravity; 
we  have  no  distinct  sensation  for  either  separately.  Why 
then  is  there  any  difference  in  the  essence  of  the  two? 
Why  not  consider  them  both  as  brought  into  our  equations 
by  the  agency  of  mathematical  transformations?  This  is 
Einstein's  point  of  view. 

Granting,  then,  the  principle  of  equivalence,  we  can  so 
choose  axes  at  any  point  at  any  instant  that  the  gravita- 
tional field  will  disappear;  these  axes  are  therefore  of 
what  are  called  the  "Galilean"  type,  the  simplest  possible. 
Consider,  that  is,  an  observer  in  a  box,  or  compartment, 
which  is  falling  with  the  acceleration  of  the  gravitational 
field  at  that  point.  He  would  not  be  conscious  of  the  field. 
If  there  were  a  projectile  fired  off  in  this  compartment, 
the  observer  would  describe  its  path  as  being  straight.  In 
this  space  the  infinitesimal  interval  between  two  space- 
time  points  would  then  be  given  by  the  formula 


ds^  =  dx\  +  dx\  +  dx^. 


4> 


EINSTEIN'S  LAW  OF  GRAVITATION      241 

where  ds  is  the  interval  and  x^,  x^,  x^,  x^,  are  coordinates. 
If  we  make  a  mathematical  transformation,  i.e.,  use  an- 
other set  of  axes,  this  interval  would  obviously  take  the 
form 

ds"  =  g^^dx''^  +  ^22^-^%  +  Qzzdx""^  +  g^^dx""^  + 
2g^^dx^dx^  +  etc., 

where  x^,  x^,  x^  and  x^^  are  now  coordinates  referring-  to 
the  new  axes.  This  relation  involves  ten  coefficients,  the 
coefficients  defining  the  transformation. 

But  of  course  a  certain  dynamical  value  is  also  attached 
to  the  ^'s,  because  by  the  transfer  of  our  axes  from  the 
Galilean  type  we  have  made  a  change  which  is  equivalent 
to  the  introduction  of  a  gravitational  field;  and  the  ^'s 
must  specify  the  field.  That  is,  these  ^'s  are  the  expres- 
sions of  our  experiences,  and  hence  their  values  cannot 
depend  upon  the  use  of  any  special  axes ;  the  values  must 
be  the  same  for  all  selections.  In  other  words,  the  expres- 
sion of  the  facts  of  gravitation  is  really  a  statement  in- 
volving a  relation  between  the  ^'s ;  and  this  expression 
must  be  the  same  for  all  sets  of  coordinates.  There  are 
ten  ^*s  defined  by  differential  equations ;  so  we  have  ten 
covariant  equations.  Einstein  showed  how  these  ^'s  could 
be  regarded  as  generalized  potentials  of  the  field.  Our 
own  experiments  and  observations  upon  gravitation  have 
given  us  a  certain  knowledge  concerning  its  potential; 
that  is,  we  know  a  value  for  it  which  must  be  so  near  the 
truth  that  we  can  properly  call  it  at  least  a  first  approxi- 
mation. Or,  stated  differently,  if  Einstein  succeeds  in 
deducing  the  rigid  value  for  the  gravitational  potential  in 
any  field,  it  must  degenerate  to  the  Newtonian  value  for 
the  great  majority  of  cases  with  which  we  have  actual 
experience.  Einstein's  method,  then,  was  to  investigate 
the  functions  (or  equations)  which  would  satisfy  the 
mathematical  conditions  just  described.  A  transforma- 
tion from  the  axes  used  by  the  observer  in  the  falling  box 


242  CONTEMPORARY  SCIENCE 

may  be  made  so  as  to  introduce  into  the  equations  the 
gravitational  field  recognized  by  an  observer  on  the  earth 
near  the  box;  but  this,  obviously,  would  not  be  the  gen- 
eral gravitational  field,  because  the  field  changes  as  one 
moves  over  the  surface  of  the  earth.  A  solution  found, 
therefore,  as  just  indicated,  would  not  be  the  one  sought 
for  the  general  field;  and  another  must  be  found  which 
is  less  stringent  than  the  former  but  reduces  to  it  as  a 
special  case.  He  found  himself  at  liberty  to  make  a 
selection  from  among  several  possibilities,  and  for  sev- 
eral reasons  chose  the  simplest  solution.  He  then  tested 
this  decision  by  seeing  if  his  formulae  would  degenerate 
to  Newton's  law  for  the  limiting  case  of  velocities  small 
when  compared  with  that  of  light,  because  this  condition 
is  satisfied  in  those  cases  to  which  Newton's  law  applies. 
His  formulae  satisfied  this  test,  and  he  therefore  was  able 
to  announce  a  "law  of  gravitation,"  of  which  Newton's 
was  a  special  form  for  a  simple  case. 

To  the  ordinary  scholar  the  difiiculties  surmounted  by 
Einstein  in  his  investigations  appear  stupendous.  It  is 
not  improbable  that  the  statement  which  he  is  alleged  to 
have  made  to  his  editor,  that  only  ten  men  in  the  world 
could  understand  his  treatment  of  the  subject,  is  true.  I 
am  fully  prepared  to  believe  it,  and  wish  to  add  that  I 
certainly  am  not  one  of  the  ten.  But  I  can  also  say  that, 
after  a  careful  and  serious  study  of  his  papers,  I  feel  con- 
fident that  there  is  nothing  in  them  which  I  cannot  under- 
stand, given  the  time  to  become  familiar  with  the  special 
mathematical  processes  used.  The  more  I  work  over  Ein- 
stein's papers,  the  more  impressed  I  am,  not  simply  by  his 
genius  in  viewing  the  problem,  but  also  by  his  great  tech- 
nical skill. 

Following  the  path  outlined,  Einstein,  as  just  said, 
arrived  at  certain  mathematical  laws  for  a  gravitational 
field,  laws  which  reduced  to  Newton's  form  in  most  cases 
where  observations  are  possible,  but  which  led  to  different 
conclusions  in  a  few  cases,  knowledge  concerning  which 


EINSTEIN'S  LAW  OF  GRAVITATION      243 

we  might  obtain  by  careful  observations.    I  shall  mention 
a  few  deductions  from  Einstein's  formulae. 

1.  If  a  heavy  particle  is  put  at  the  center  of  a  circle, 
and,  if  the  length  of  the  circumference  and  the  length  of 
the  diameter  are  measured,  it  will  be  found  that  their 
ratio  is  not  tt  (3.14159).  In  other  words  the  geometrical 
properties  of  space  in  such  a  gravitational  field  are  not 
those  discussed  by  Euclid ;  the  space  is,  then,  non-Euclid- 
ean. There  is  no  way  by  which  this  deduction  can  be  veri- 
fied, the  difference  between  the  predicted  ratio  and  ^  is  too 
minute  for  us  to  hope  to  make  our  measurements  with 
sufficient  exactness  to  determine  the  difference.  * 

2.  All  the  lines  in  the  solar  spectrum  should  with  refer- 
ence to  lines  obtained  by  terrestrial  sources  be  displaced 
slightly  towards  longer  wave-lengths.  The  amount  of  dis- 
placement predicted  for  lines  in  the  blue  end  of  the  spec- 
trum is  about  one-hundredth  of  an  Angstrom  unit,  a 
quantity  well  within  experimental  limits.  Unfortunately, 
as  far  as  the  testing  of  this  prediction  is  concerned,  there 
are  several  physical  causes  which  are  also  operating  to 
cause  displacement  of  the  spectrum-lines ;  and  so  at  pres- 
ent a  decision  cannot  be  rendered  as  to  the  verification. 
St.  John  and  other  workers  at  the  Mount  Wilson  Obser- 
vatory have  the  question  under  investigation. 

3.  According  to  Newton's  law  an  isolated  planet  in  its 
motion  around  a  central  sun  would  describe,  period  after 
period,  the  same  elliptical  orbit;  whereas  Einstein's  laws 
lead  to  the  prediction  that  the  successive  orbits  traversed 
would  not  be  identically  the  same.  Each  revolution  would 
start  the  planet  off  on  an  orbit  very  approximately  ellipti- 
cal, but  with  the  major  axis  of  the  ellipse  rotated  slightly 
in  the  plane  of  the  orbit.  When  calculations  were  made 
for  the  various  planets  in  our  solar  system,  it  was  found 
that  the  only  one  which  was  of  interest  from  the  stand- 
i^oint  of  verification  of  Einstein's  formulae  was  Mercury. 
It  has  been  known  for  a  long  time  that  there  was  actually 
such  a  change  as  just  described  in  the  orbit  of  Mercury, 


244  CONTEMPORARY  SCIENCE 

amounting  to  574*^  of  arc  per  century;  and  it  has  been 
shown  that  of  this  a  rotation  of  532"  was  due  to  the  direct 
action  of  other  planets,  thus  leaving  an  unexplained  rota- 
tion of  42"  per  century.  Einstein's  formulae  predicted  a 
rotation  of  43",  a  striking  agreement. 

4.  In  accordance  with  Einstein's  formulae  a  ray  of 
light  passing  close  to  a  heavy  piece  of  matter,  the  sun,  for 
instance,  should  experience  a  sensible  deflection  in  to- 
wards the  sun.  This  might  be  expected  from  "general" 
considerations.  A  light  ray  is,  of  course,  an  illustration 
of  energy  in  motion ;  energy  and  mass  are  generally  con- 
sidered to  be  identical  in  the  sense  that  an  amount  of 
energy  E  has  the  mass  E/c^  where  c  is  the  velocity  of 
light;  and  consequently  a  ray  of  light  might  fall  within 
the  province  of  gravitation  and  the  amount  of  deflection  to 
be  expected  could  be  calculated  by  the  ordinary  formula 
for  gravitation.  Another  point  of  view  is  to  consider 
again  the  observer  inside  the  compartment  falling  with  the 
acceleration  of  the  gravitational  field.  To  him  the  path 
of  a  projectile  and  a  ray  of  light  would  both  appear 
straight ;  so  that,  if  the  projectile  had  a  velocity  equal  to 
that  of  light,  it  and  the  light  wave  would  travel  side  by 
side.  To  an  observer  outside  the  compartment,  eg,,  to 
one  on  the  earth,  both  would  then  appear  to  have  the 
same  deflection  owing  to  the  sun.  But  how  much  would 
the  path  of  the  projectile  be  bent?  What  would  be  the 
shape  of  its  parabola?  One  might  apply  Newton's  law; 
but,  according  to  Einstein's  formulae,  Newton's  law  should 
be  used  only  for  small  velocities.  In  the  case  of  a  ray 
passing  close  to  the  sun  it  was  decided  that  according  to 
Einstein's  formula  there  should  be  a  deflection  of  i".75 
whereas  Newton's  law  of  gravitation  predicted  half  this 
amount.  Careful  plans  were  made  by  various  astrono- 
mers to  investigate  this  question  at  the  solar  eclipse  last 
May,  and  the  result  announced  by  Dyson,  Eddington  and 
Crommelin,  the  leaders  of  astronomy  in  England,  was 
that  there  was  a  deflection  of  i\g.    Of  course  the  detec- 


EINSTEIN'S  LAW  OF  GRAVITATION      245 

tion  of  such  a  minute  deflection  was  an  extraordinarily 
difficult  matter,  so  many  corrections  had  to  be  applied  to 
the  original  observations ;  but  the  names  of  the  men  who 
record  the  conclusions  are  such  as  to  inspire  confidence. 
Certainly  any  effect  of  refraction  seems  to  be  excluded. 

It  is  thus  seen  that  the  formulae  deduced  by  Einstein 
have  been  confirmed  in  a  variety  of  ways  and  in  a  most 
brilliant  manner.  In  connection  with  these  formulae  one 
question  must  arise  in  the  minds  of  everyone:  by  what 
process,  where  in  the  course  of  the  mathematical  develop- 
ment, does  the  idea  of  mass  reveal  itself?  It  was  not  in 
the  equations  at  the  beginning  and  yet  here  it  is  at  the 
end.  How  does  it  appear  ?  As  a  matter  of  fact  it  is  first 
seen  as  a  constant  of  integration  in  the  discussion  of  the 
problem  of  the  gravitational  field  due  to  a  single  particle ; 
and  the  identity  of  this  constant  with  mass  is  proved  whei\ 
one  compares  Einstein's  formulae  with  Newton's  law  which 
IS  simply  its  degenerated  form.  This  mass,  though,  is  the 
mass  of  which  we  become  aware  through  our  experiences 
with  weight;  and  Einstein  proceeded  to  prove  that  this 
quantity  which  entered  as  a  constant  of  integration  in  his 
ideally  simple  problem  also  obeyed  the  laws  of  conserva- 
tion of  mass  and  conservation  of  momentum  when  he  in- 
vestigated the  problems  of  two  and  more  particles. 
Therefore  Einstein  deduced  from  his  study  of  gravita- 
tional fields  the  well-known  properties  of  matter  which 
form  the  basis  of  theoretical  mechanics ;  i.e.,  he  established 
the  identity  of  gravitational  and  inertial  mass.  A  further 
logical  consequence  of  Einstein's  development  is  to  show 
that  energy  has  mass,  a  concept  with  which  everyone 
nowadays  is  familiar. 

The  description  of  Einstein's  method  which  I  have  given 
so  far  is  simply  the  story  of  one  success  after  another; 
and  it  is  certainly  fair  to  ask  if  we  have  at  last  reached 
finality  in  our  investigation  of  nature,  if  we  have  attained 
to  truth.  Are  there  no  outstanding  difficulties?  Is  there 
no  possibility  of  error?    Certainly,  not  until  all  the  pre^ 


246  CONTEMPORARY  SCIENCE 

dictions  made  from  Einstein's  formulae  have  been  inves- 
tigated can  much  be  said;  and  further,  it  must  be  seen 
whether  any  other  lines  of  argument  will  lead  to  the  same 
conclusions.  But  without  waiting  for  all  this  there  is  at 
least  one  difficulty  which  is  apparent  at  this  time.  We 
have  discussed  the  laws  of  nature  as  independent  in  their 
form  of  reference  axes,  a  concept  which  appeals  strongly 
to  our  philosophy ;  yet  it  is  not  at  all  clear,  at  first  sight, 
that  we  can  be  justified  in  our  belief.  We  cannot  imagine 
any  way  by  which  we  can  become  conscious  of  the  trans- 
lation of  the  earth  in  space ;  but  by  means  of  gyroscopes 
we  can  learn  a  great  deal  about  its  rotation  on  its  axis. 
We  could  locate  the  positions  of  its  two  poles,  and  by 
watching  a  Foucault  pendulum  or  a  gyroscope  we  can  ob- 
tain a  number  which  we  interpret  as  the  angular  velocity 
of  rotation  of  axes  fixed  in  the  earth;  angular  velocity 
with  reference  to  what?  Where  is  the  fundamental  set 
of  axes?  This  is  a  real  difficulty.  It  can  be  surmounted 
in  several  ways.  Einstein  himself  has  outlined  a  method 
which  in  the  end  amounts  to  assuming  the  existence  on 
the  confines  of  space  of  vast  quantities  of  matter,  a  propo- 
sition which  is  not  attractive.  deSitter  has  suggested  a 
peculiar  quality  of  the  space  to  which  we  refer  our  space- 
time  coordinates.  The  consequences  of  this  are  most  in- 
teresting, but  no  decision  can  as  yet  be  made  as  to  the 
justification  of  the  hypothesis.  In  any  case  we  can  say 
that  the  difficulty  raised  is  not  one  that  destroys  the  real 
value  of  Einstein's  work. 

In  conclusion  I  wish  to  emphasize  the  fact,  which  should 
be  obvious,  that  Einstein  has  not  attempted  any  explana- 
tion of  gravitation ;  he  has  been  occupied  with  the  deduc- 
tion of  its  laws.  These  laws,  together  with  those  of 
electromagnetic  phenomena,  comprise  our  store  of  knowl- 
edge. There  is  not  the  slightest  indication  of  a  mecha- 
nism, meaning  by  that  a  picture  in  terms  of  our  senses. 
In  fact  what  we  have  learned  has  been  to  realize  that  our 
desire  to  use  such  mechanisms  is  futile. 


INDEX 


Ahruzsi,  Duke  of,  103 
Acapnia,  107 
Acclimatization,  105 
Adams,  F.  D.,  56 
Acidosis,  105,  106,  107 
Aircraft,  48 

"Air-staleness,"  aviators*,  96 
Allen,  92 
Altitudes,  effect  on   system  of 

high,  97,  112 
Ames,  12,  230 
Amphibians,  length  of  life  of, 

94 
Anaphylaxis,   130-135  ^ 

compared  to  immunity,  133 
Anesthesia,  154 
Anthrax,  116,  118,  119 
Antiseptics,  154 
Antitoxin,  122 
Armstrong,  82,  83 
Arrhenius,  124 
Asepsis,  185 

Association  experiment,  224 
Atom,  divisibility  of,  14 

its  nucleus,  18,  23 

structure  of,  23 
Atomic  number,  23 
Atoms,  9 
Auer,  134 
Auld,  11,  61 
Aviator,  physiology  of,  95-114 

tests  for,  109,  110,  112 


Bark  la,  19 

Bayard,  177 

Behrens,  110 

Behring,  119,  120,  122,  123,  125 

Bell,  C,  158 

Bell,  J.,  158,  159,  160,  163,  189 

Benzyl  bromide,  69 

Bert,  97 

Bertrand,  82,  83 

Beryllium,  25 

Bigelow,  129,  182 

Blowes 

Boer  War,  168 

Bogdanow,  87 

Bohr,  22,  23,  24,  25,  27,  31 

Bolin,  83 

Bordet,  124,  125,  142,  144 

Bore  hole,  56 

Born,  26 

Boulton,  36 

Bowlby,  185 

Bragg,  20,  28,  45,  47 

Brain  power,  measurement  and 

utilization  of  in  the  army, 

192-210 
Brewer,  216 
Briggs,  173,  174 
Bristowe,  163 
Bryant,  177 
Buchner,  77,  80 
Burrell,  114 
Burrow,  12,  211 


Bacon,  58 

Bacteriology,  11,  115-151 


Caisson  disease,  98 
Cameron,  160 


247 


248 


CONTEMPORARY  SCIENCE 


Campbell,  174,  175 
Cancer  research,  140,  141 
Canniff,  173 
Carbolic  acid,  167,  174 
Carbon,  23 

See  charcoal 
Carnot,  35 
Carpenter,  173 
Carrel,  91,  186 

Carrel-Dakin  method  of  disin- 
fection, 191 
Carroll,  144 
Catalyst,  76 
Cerium,  23  ^ 
Championmire,  17S 
Charcoal,  68 
Chemical    reactions,    effect    of 

temperature  on,  88 
Chemotherapy,  145-148 
Chenu,  164,  165 
Cheyne,  186 
Chicken-pox,  137 
Chlorine,  23 

in  gas  warfare,  63 
Cholera,  119,  126 
Cinchona  bark,  146 
Civil  War,  152,  164 

casualties,  166 
Clerk,  41 
Coal,  53 
Colloids,  79,  80 

Complex  salts,  structure  of,  30 
Cooper,  183 
Crewe,  58 
Crimean  War,  164 

casualties,  165 
Croce-Spinelli,  103 
Crommelin,  244 
Crystal  structure,  19 
Crystalloids,  79 
Cultivation     of     bacterial 

growths,  119 
Curie,  Madame,  9 

Dalton,  9 
Davaine,  116,  119 


Dawson,  175 
Death,  cause  of,  86 

meaning  of,  88 

natural,  and  the  duration  of 
life,  85-94 
Delorme,  188 
Democritus,  13 
Dennis,  179 
Dernhy,  86 
Diphtheria,   115,   119,    120,   121, 

123 
Disintegration,  body,  85,  86 
Dodge,  193 
Douglas,  103 
Dreams,  significance  of,  220 

analysis  of,  221 
Duane,  22 
Duncan,  164,  165 
Dunlap,  110 
Dysentary,  119 
Dyson,  244 

Eddington,  244 

Ehrlich,  122,  124,  125,  147,  186 
Einstein,  230,  231,  233,  234,  235, 
236,  239,  240,  241,  242,  243, 
244,  245,  246 
Einstein's  theory,  12 

law  of  gravitation,  230-246 

deductions,  243 
Electricity,  14,  50 
Electron,  10,  17,  21 
Elements,  relations  between,  20 
Enzymes,  11,  76-84 

as  catalysts,  76 

isolation  of,  78,  80-84 

"specificity"^  of,  78 

characteristic  properties,  79 
Erichsen,  154 
Erosion  of  propellers,  57 
Estes,  163 
Euclid,  243 
Euler,  83 

Folk,  84 

Fehling's  solution,  78 


INDEX 


249 


Ferments,  77 

See  enzjrmes 
Filippi,  103 
Filterables,  135-141 
Fischer,  78,  83 
Fitzgerald,  105 
Flexner,  11,  115,  130,  138 
Flies,  aseptic,  87,  88 
duration  of  life  of,  89 
influence  of  temperature  on, 

94 
Fluorine,  27,  32 
Fluosilicate  ion,  29 
Forchheimer,  215 
Fourth  dimension.  234 
Fowl  cholera,  117,  118 
Fraenkel,  80 

Franco-Prussian  War,  167 
Freud,  212,  214,  215,   216,  217, 

218,  219,  220,  221,  222,  223, 

226,  227,  228 
Frog,  metamorphosis  of,  92 
Frosch,  136 
Fruit  fly,  metamorphosis  of,  93 

Galen,  157 

Gas  masks,  11 

Gas  shells,  67,  69,  70 

advantages,  70 

their  future,  73 
Gas  warfare,  11,  61-75 

compounds  used,  74 

early  methods,  62 

protection  against,  64,  68 
Gaseous  explosions,  41 
Gates,  138 
Geiger,  18 

Germ  theory,  172-191 
Gibbs,  111 
Girard,  173 
Gorgas,  165 
Graham,  79,  80 
Gravitation,  238 

Einstein's  law  of,  242 
Great  Eastern  (ship),  38 
Gudematsch,  92,  93 


Guerin,  159 
Guinea-pig,  132 
Guyinot,  87 

Hadfield,  40 

Haggard,  106,  107 

Haldane,  103,  104,  105 

Hamilton,  F.,  173 

Harrow,  9,  76 

Hartmann,  188 

Hay  fever,  123,  134 

Heath,  58 

Helium,  23,  25 

Henderson,  L.  J.,  104 

Henderson,  Y.,  11,  95,  103,  106, 

107 
Hewitt^  177 
Hewson,  173 

Hexamethylenetetramine,  67,  74 
Hodgen,  173 
Holmes,  O.  W.,  161 
Holmes,  T„  163,  176 
Hopkinson,  41 
Hospital  gangrene,  160,  167, 180, 

181 
Hospitals,  at  present,  163,  169, 
state  of,  several  decades  ago, 

159,  162,  163 
Hull,  20,  29 
Hunt,  22 
Hydrogen,  23,  32 

Immunity,  115-130 
Infantile  paralysis,  137,  138 
Infection,  148-151,  174 
Influenza,  150 

Intelligence,  methods  of  meas-< 
uring,  196-198 
relation  to  occupation,  208 
Ion,  28 
Isosteric  substances,  33 

Jackson,  165 
James,  W„  228 


250 


CONTEMPORARY  SCIENCE 


Jaundice,  144 
Jenn^,  117,  118 
Johnson,  156 
Joule,  35 
Jung,  224,  226 

Keen,  11,  152,  153,  166,  182 

Keith,  46 
Kelvin,  35»  53 
Kinloch,  173,  175 
Kitasato,  J20 
Kitchener,  64 
iTor/j,  119,  179 
Kossel,  30 
KUhne,  77 

Laccase,  83 

Lachrymators,  ^S,  69,  71,  73 

Lacomhle,  30 

Lands,  24,  26 

Lang,  111 

Langevin,  47 

Langmuir,  10,  23 

Larmor,  230 

Larrey,  182 

Laue,  19 

Lavoisier,  9,  108 

Lebailly,  138 

Lemaire,  170 

Lentner,  81 

Lewis,  24,  31 

Life,  definition,  85 

duration  of,  91 

prolonging,  85 
Ligature,  156 
Lindpainter,  181 
Lipases,  84 

Lwf^n    11,    154,    160,    161,    170, 
171-173,  175,  191 

applies     antiseptic     methods, 
178 

before  and  after,  152-191 
Lithium,  23,  25 
Lo^&,  /.,  11,  85,  87,  89 
Lo^6,  L.,  91 
Loeffler,  136 


Lorents,  230,  233,  234,  236 
Luetin,  135 
Lynch,  168 

McGraw,  175 

McGrigor,  164 

Magendi,  130 

Magnesium,  28,  30 

Mahan,  95 

Malgaigne,  156,  163 

Manganese,  83 

Manganese  dioxide,  76 

Markoe,  173 

Marsden,  18 

Martin,  183 

Matter,  kinetic  theory  of,  13 
electrical  origin  of,  16 

Maunder,  176 

Maxim,  47 

Maxwell,  53,  230,  233 

May  OS,  183 

Measles,  137 

Meningitis,  119,  126,  127 

Mental    examinatioii,    purpose 
of,  194 
reliability  of  methods,  198 
summary  of  results,  200 

Mercury,   146 

Metchnikoff,  88,   122,   124,   125, 
142,  144 

Millikan,  10,  13,   15,  22 

Minkowski,  234,  235,  237 

Moore,  174 

Mosely,  20,  21 

Motley,  164 

Afoff,  182 

Mountain   sickness,   98 

Mumford,  184 

Murphy,  140 

Muschet,  40 

Mustard  gas,  72 

Nancrede,  175 
Neon,   23,   28,   29 
Neurosis,  215,  218,  219 
Newcomen,  35 


INDEX 


251 


Newton,  239,  242,  243,  244 

Nickel,  23 

Nicolaier,  120 

Nicolle,  138 

Nightingale,   164 

Nitrogen,  in  Caisson's  disease, 

98 
Noguchi,  138,  142,  143,  144 
Northrop,  87,  89 
Nucleus    of    the    atom.      See 

atom,  its  nucleus 
Nusshaum,  172,   180 

Octet  group  of  electrons,  26 

Old  age,  cause  of,  88 

Olitzky,  138 

Operations,  types  of,  182-184 

Osborne,  80,  81 

Ostwald,  13 

Oxidases,  83 

Oxygen,  28,  76 

at  high  altitudes,  97,  111 

lack  of,  101 

Paget,  46,  177 

Pancoast,  182 

Panzer,  83 

Pare,  155,  156,  157,  170,  189 

Parson,  24 

Parsons,  10,  34 

Passive  immunization,  122 

Pasteur,   11,   77,   116,   117,   118, 

119,  120,  131,  161,  170 
Paton,  110 

Paul  the  Apostle,  154 
Peckelharing,  80 
Peninsula  campaign,  164 
Pfeiffer,   138 

Phenylcarbylamine  chloride,  73 
Phosgene,  64,  67 

protection  against,  65,  67 
Phosphorus,  29 
Phosphorus  pentafluoride,  29 
Pierce,  110 
Plague,  119,  126 
Planck,  27 


Pneumonia,  126,  127 

Potassium  chlorate,  76 

Pouchet,  170 

Preece,  41 

Pressure,  changes  of,  99^  100 

Prince,  175 

"Principle  of  Equivalence,"  239 

Prussic  acid,  68 

Psychanalytic  method,  212 

basic  principles,  215-220 
Psychoanalysis,  conceptions  and 
misconceptions,  211-229 

technic,  222 

uses  of,  226 

what  is  is  not,  213,  214 
Psychologists,  in  the  army,  193 
Ptomaines,*  121 
Pyemia,   166,   180 
Quantum  relations,  22 

theory,  27 
Queen    Elizabeth    (battleship), 
43 

Rabies,  117,  118 

Radio-activity,  14 

Radium,  23 

Reed,  144 

Research,  value  of,  58 

Respiration,  108 

Respirator,  67,  73,  74 

Richardson,  46 

Richet,   131 

Riviere,  156 

Roentgen,  9 

Rohan,  157 

Rous,  141 

Roux,  120 

Rowland,  16,  188 

Russell,  39 

Russo-Japanese  War,  168 

Rutherford,  10,  18,  23,  63 

Ryan,  45 

Salamanders,       metamorphosis 

of,  93,  94 
Salvarsan,  147 


252 


CONTEMPORARY  SCIENCE 


Satterthwaite,  173 

Savory,  177 

Saxtorph,  172 

Scarlet  fever,  137 

Schaudinn,  142,   144 

Schick  test,  123,  135 

Schneider,  10^,  110 

Semmelweiss,  161 

"Serum  sickness,"  134 

Serum  therapy,  122 

Sexual  life,  possible  courses  in 

the  development  of,  217 
Sherman,  80,  81 
Silver,  23 

Simpson,  161,  162,  165,  189 
Sleeping:  sickness,  147 
Smallpox,  117 
"Sneezing  gas,"  73 
Sodium,  28 
Sodium  fluoride,   structure  of, 

28 
Sodium  phenate,  65,  67 
Sound    ranging    and    listening 

devices,  44 
Soutfar,  187 

Spanish- American  War,  168 
Spence,  177 
Spirochetes,   141-145 
Splenic  fever,  116 
Steam,  laws  of,  34 
Sulfur,  30 

Sulphur  hexafluoride,  29 
Stark,  24,  31 
Steam  engine,  34,  35 
Stewart,  176 
Stimson,  144 
Strong,  165 
Sucrase,  78 
Swingle,  93 
Syme,  172,   179,   182 
Syphilis,  135,  142,  146 

Tait,  177 

Taylor,  40 

"Tear"  shells,  69 

Tetanus,  119,  120,  121,  167,  187 


Teudt,  30 
Thiersch,  172 
Thomson,  J.  J.,  9,  16,  31 
Thyroid  gland,  92,  93 
Tissandier,   101,   103 
Titanic   (ship),  46 
Toxalbumins,  121 
Trelat,  163 
Trench   fever,  137 
Trichloromethylchloroformate 

in  gas  shells,  70 
Trillat,  83 
Tuberculin,  135 
Tuberculosis,  119,  126,  135 
Tungsten,  23 
Tungsten  steel,  40 
Turbines,  36-38 
Tyndall,  143 
Typhoid  fever,  119,  123,  126,  188 

Uhlenhuth,  94 
Ultra-microscope,  142 
Uranium,  23 
Urotropine,  67 

Vaccination,   against  smallpox, 
117 

Valence,  chemical,  27,  32 
maximum,  positive  and  nega- 
tive, 30 

Van  Buren,  173 

Van  Slyke,  106 

Voigt,  230 

Voikmann,  172,  180 

War  casualties,  164 

Wassermann  reaction,  123 

Water  power,  53 

Watt,  34,  35,  36,  37 

Werner,  30 

White,  M.,  40 

White,  Sir  W.,  38,  39,  45 

Whitney,  110 

Widal  test,  123 

Wilmer 

Woker,  84 


INDEX  25:, 

Wolf,  83  Xenon,  26 

*World-line,"  Minkowski's,  236      Xylyl  bromide,  69 
Wrench,  154,  176 
Wright,  186  Yellow  fever,  137,  142,  144 

Yerkes,  12,  192 
X-rays,  14,  19,  21  Yersin,  120 


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r 


Harrow,  B. 


_Q111. 
H2a 


Contemporkry  science. 


Hs-vr^W 


a//i 

HE6 


104256 


STATIONERY 
'''OAKLAND  CAL 


